Rozprawy doktorskie na temat „Aging cardiac”

The left ventricle of the heart relaxes when it fills with blood and contracts to eject blood into circulation to meet the body’s metabolic demands. Dysfunction in either relaxation or contraction of the left ventricle can lead to heart failure. Transmural heterogeneity is thought to contribute to normal ventricular wall motion but it is not well understood how transmural modifications affect the failing left ventricle. The overall hypothesis of this dissertation is that normal left ventricles exhibit transmural heterogeneity in cellular level contractile properties and with aging and heart failure there are region-specific changes in cellular level contractile mechanisms. Age is the biggest risk factor associated with heart failure and therefore we investigated transmural changes in Ca2+ handling and contractile proteins in aging F344 rats before the onset of heart failure. We found that in 22-month old F344 rats there is a region-specific decrease in cardiac troponin I phosphorylation in the sub-epicardium that may contribute to slowed myocyte relaxation in the sub-epicardial cells of the same age. We then investigated the transmural patterns of contractile properties in myocardial tissue samples from patients with heart failure. Force and power output reduced most significantly in the samples from the mid-myocardial region when compared to sub-epicardium and sub-endocardium of the failing hearts. There was a region-specific increase in fibrosis is the mid-myocardium of the failing hearts. Myocardial power output was correlated with key sarcomeric proteins including cardiac troponin I, desmin and myosin light chain-1. The results in this dissertation reveal novel region-specific modifications in contractile properties in aging and heart failure. These transmural effects can potentially contribute to disruption in normal wall motion and lead to ventricular dysfunction.

Obesity is closely related to many medical complications such as type 2 diabetes, hypertension and heart failure. Obesity and other factors, including elevated blood glucose levels, hypertension, and dyslipidemia, constitute a constellation of symptoms known as the metabolic syndrome, which are the risk factors for coronary artery disease. Lipocalin-2 is a pro-inflammatory adipokine causally involved in the development of obesity-associated metabolic and cardiovascular diseases. Recent clinical and experimental evidences demonstrate an association between augmented circulating lipocalin-2 and cardiac dysfunction. However, little is known about the detailed roles of lipocalin-2 in regulating pathophysiological functions of the heart. The present study was designed to compare the heart functions of mice with normal (WT) or deficient lipocalin-2 (Lcn2-KO) expression and to examine the molecular mechanisms underlying lipocalin-2-mediated deteriorated effects in hearts. Echocardiographic analysis revealed that the myocardial contractile function was significantly improved in hearts of Lcn2-KO mice, under both standard chow and high fat diet conditions. The heart function before and after I/R injury (20-min of global ischemia followed by 60-min of reperfusion) was assessed using the Langendorff perfusion system. Compared with WT littermates, hearts from Lcn2-KO mice showed improved functional recovery and reduced infarct size following I/R. These phenomena can be observed in mice under both standard chow and high fat feeding conditions. Under baseline condition, the mitochondrial function of hearts from Lcn2-KO mice was significantly enhanced, as demonstrated by biochemical analysis of respiratory chain activity, markers of biogenesis and oxidative stress, as well as electron microscopic investigation of the mitochondrial ultrastructure. Acute or chronic administration of lipocalin-2 impaired cardiac functional recovery to I/R and dampened the mitochondrial function in hearts of Lcn2-KO mice. These effects were associated with an extensive modification of the fatty acyl chain compositions of intracellular phospholipids. In particular, lipocalin-2 facilitated the redistribution of linoleic acid (C18:2) among different types of phospholipid, including cardiolipin, which is exclusively located in the mitochondria inner membrane. The direct effects of lipocalin-2 on both H9c2 and NCM cells were also examined. TUNEL assay and flow cytometry analysis demonstrated that lipocalin-2 treatment promoted apoptosis in cardiomyocytes. Lipocalin-2 induced an early phase of phosphatidylserine exposure, followed by Bax-translocation and caspase-3 cleavage. The results collectively suggested that lipocalin-2 initiated the intrinsic mitochondria-mediated apoptotic pathway. In the hearts of Lcn2-KO mice, significantly reduced number of apoptotic cells was observed after I/R injury. In conclusion, lacking of lipocalin-2 improved heart function recovery during I/R injury via mitochondrial function restoration, phospholipids remodeling, and inhibition of cardiomyocytes apoptosis.
published_or_final_version
Pharmacology and Pharmacy
Doctoral
Doctor of Philosophy

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第10300号
人博第187号
14||151(吉田南総合図書館)
新制||人||46(附属図書館)
UT51-2003-H721
京都大学大学院人間・環境学研究科文化・地域環境学専攻
(主査)教授 森谷 敏夫, 教授 中村 榮太郎, 教授 津田 謹輔
学位規則第4条第1項該当

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第10299号
人博第186号
14||150(吉田南総合図書館)
新制||人||45(附属図書館)
UT51-2003-H720
京都大学大学院人間・環境学研究科文化・地域環境学専攻
(主査)教授 森谷 敏夫, 教授 津田 謹輔, 教授 田口 貞善
学位規則第4条第1項該当

Many senescent individuals demonstrate an inability to regulate mean arterial pressure (MAP) in response to standing or head-up tilt; however, whether this aging effect is the result of depressed cardiac function or an inability to reduce peripheral vascular conductance remains unknown. Therefore, the purpose of this research was to investigate the effects of aging on MAP, heart rate (HR), regional blood flow (via radioactive-microspheres), and vascular conductance during head-up tilt in conscious young (4 mo; n=12) and old (24 mo; n=10) male Fischer-344 rats. Heart rate and MAP were measured continuously during normal posture and during 10 minutes of head-up tilt. Blood flow was determined during normal posture and at the end of 10 minutes of head-up tilt. Young rats increased MAP significantly at the onset of head-up tilt and generally maintained the increase in MAP for the duration of head-up tilt, while aged rats showed a significant reduction in MAP after 10 minutes of head-up tilt. In the normal posture, aged rats demonstrated lower blood flow to splanchnic, bone, renal, and skin tissues versus young rats. With tilt there were decreases in blood flow to skin, bone, and hind-limb in both age groups and in fat, splanchnic, reproductive, and renal tissues in the young. Bone blood flow was attenuated with age across both conditions in hind foot, distal femur, femur marrow, and proximal and distal tibia. Head-up tilt caused a decrease in blood flow across both age groups in all bones sampled with the exception of the hind foot. These results provide evidence that the initial maintenance of MAP in aged rats during head-up tilt occurs through decreased regional blood flow and vascular conductance, and that the fall in pressure is not attributable to an increase in tissue blood flow and vascular conductance. Therefore, reductions in arterial pressure during headup tilt are likely a result of an old age-induced reduction in cardiac performance. In addition, this is the first study to demonstrate a decreased bone vascular conductance in both young and old rats during head-up tilt.

Nel corso del mio dottorato sono stata coinvolta principalmente in due progetti con lo scopo di studiare la disfunzione cardiaca indotta da invecchiamento o chemioterapia. Il primo studio aveva lo scopo di riprodurre e caratterizzare i meccanismi dell’invecchiamento utilizzando cardiomiociti (CMs) da cellule staminali pluripotenti indotte umane (hiPSCs) e inoltre testare terapie cardioprotettive, come gli esosomi (Exo) da cellule progenitrici cardiache (CPCs). L’invecchiamento cardiaco coinvolge rimodellamenti a livello dei singoli CMs che predispongono allo scompenso cardiaco e la cui incidenza aumenta con l’avanzare dell’età. Curiosamente, fino ad ora non è stato ancora sviluppato un modello di invecchiamento cardiaco umano. Abbiamo riprogrammato CPCs umane ad iPSC e successivamente le abbiamo differenziate in CMs. Un fenotipo simile alla senescenza (SenCMs) è stato indotto con un breve trattamento (3 ore) con doxorubicina (Dox) a concentrazioni sub-letali (0.2 µM). 24 ore dopo il trattamento, alcuni SenCMs sono stati esposti ad Exo (~2·10^3 particelle/cellula) isolati dal medium di coltura delle CPCs. Il trattamento con Dox induce senescenza, come confermato dall’attivazione di p21 e dalla maggiore positività a SA-β-gal in confronto ai controlli (cCMs). Analisi biochimiche hanno rivelato la presenza di stress ossidativo e un potenziale di membrana mitocondriale depolarizzato nei SenCMs, con una ridotta produzione di ATP dai mitocondri. I SenCMs hanno anche difetti nel calcium handling e un QTc prolungato a causa dell’aumento di INaL. Questi effetti sono mitigati dal trattamento con Exo. Complessivamente, i SenCMs ricapitolano il fenotipo dei CMs invecchiati in termini di markers di senescenza e proprietà elettriche e metaboliche. Inoltre, l’esposizione ad Exo prodotti da CPCs limita molte delle anomalie cardiache indotte dall’invecchiamento. Il secondo studio mirava a valutare la disfunzione cardiaca causata dalla somministrazione in combinazione di Dox e Trastuzumab (Trz) in miociti cardiaci di ratto. Il trattamento combinato con Dox e Trz in pazienti con cancro al seno è limitato a causa della cardiotossicità, che si manifesta con disfunzione contrattile ed aritmie. Il ruolo specifico dei due agenti nella cardiotossicità causata dalla terapia combinata è però non ancora del tutto chiarito. I ratti hanno ricevuto 6 dosi di Dox, Trz o entrambi in maniera sequenziale. La disfunzione del ventricolo sinistro (LV) mediata da Dox era aggravata dalla somministrazione di Trz. Il trattamento con Dox, ma non con Trz, induceva danno ai tubuli T, prolungamento della durata del potenziale d’azione (APD), aumento dell’incidenza di post-depolarizzazioni tardive (DADs), decadimenti dei transienti di Ca2+ più lenti e la fuoriuscita di Ca2+ dal reticolo in Ca2+ sparks o Ca2+ embers. Il trattamento in combinazione esacerbava queste anomalie. Trz, ma non Dox, riduceva l’ampiezza dei transienti di Ca2+ e il contenuto di Ca2+ nel reticolo sarcoplasmatico (SR). Entrambi gli agenti aumentavano le onde di Ca2+ spontanee e diminuivano l’espressione di SERCA. Questi risultati suggeriscono che Dox, ma non Trz, potrebbe causare danno ai tubuli T in vivo e, inoltre, indurre cambiamenti nei parametri elettrici e nel Ca2+-handling. Mentre Dox induceva cambiamenti reversibili nei parametri elettrofisiologici, la successiva somministrazione di Trz impediva il rescue. Questi risultati illustrano il ruolo specifico di Dox e Trz e il loro ruolo nella cardiotossicità.
During my PhD I was involved mainly in two research projects aimed to study myocardial dysfunction induced by aging or chemotherapy. The first study aimed to reproduce and characterize mechanisms involved in aging using cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs), and to test cardioprotective therapies, like cardiac progenitor cell (CPC)-derived exosomes (Exo). Aging of the heart involves adverse remodeling in CMs which results in heart failure with incidence that increases with age. Interestingly, till now we lacked a human model of cardiac aging. We reprogrammed CPCs into hiPSCs and subsequently differentiated in hiPSC-derived CMs. A senescence-like phenotype (SenCMs) was induced by short exposure (3 hours) to doxorubicin (Dox) at sub-lethal concentration (0.2 µM). 24h following DOX treatment, SenCMs were exposed to Exo (~2·103 particles/cell) collected from culture media of CPCs by ultracentrifugation. Dox treatment induced senescence, as confirmed by activation of p21 and increased SA-β-gal positivity compared to control CMs (cCMs). Biochemical analysis revealed presence of oxidative stress and a depolarized mitochondrial membrane potential due to the treatment, which resulted in decreased ATP production by mitochondria. SenCMs also showed impaired calcium handling and prolonged QTc vs. cCMs due to upregulation of INaL. These effects were mitigated by exposure to Exo. Overall, SenCMs recapitulate the phenotype of aged CMs in terms of senescence markers and electrical and metabolic properties. Additionally, exposure to CPC-derived Exo limited age-related cardiac anomalies. The second study aimed to study the cardiac dysfunction dependent on the combined administration of Dox and trastuzumab (Trz) through evaluation of cardiac performance, T-tubule organization, and electrophysiological changes in cardiac myocytes from an in-vivo rat model. Combined treatment with Dox and Trz in patients with HER2-positive cancer is limited by cardiotoxicity, as manifested by contractile dysfunction and arrhythmia. The respective roles of the two agents in the cardiotoxicity of the combined therapy are incompletely understood. Adult rats received 6 doses of either Dox or Trz, or the two agents sequentially. Dox-mediated left ventricular (LV) dysfunction was aggravated by Trz administration. Dox treatment, but not Trz, induced T-tubule disarray. Moreover, Dox, but not Trz monotherapy, induced prolonged action potential duration (APD), increased incidence of delayed afterdepolarizations (DADs) and beat-to-beat variability of repolarization (BVR), and slower Ca2+ transient decay. Although APD, DADs, BVR and Ca2+ transient decay recovered over time after the cessation of Dox treatment, subsequent Trz administration exacerbated these abnormalities. Trz, but not Dox, reduced Ca2+ transient amplitude and SR Ca2+ content. Both agents increased Ca2+ waves and downregulated SERCA. Finally, Dox increased resting Ca2+ waves, Ca2+ spark frequency, spark-mediated sarcoplasmic reticulum (SR) leak, and long-lasting Ca2+ release events (so-called Ca2+ “embers”). These results suggest that Dox, but not Trz, may cause T-tubule disarray in cardiac myocytes in vivo while also inducing overall larger changes in electrical parameters and intracellular Ca2+ handling. While Dox-induced changes in electrical parameters are reversible, subsequent Trz administration prevents their recovery. These findings illustrate the specific roles of Dox and Trz, and their interactions in cardiotoxicity and arrhythmogenicity.

Background: L'invecchiamento è un inevitabile fattore di rischio in età avanzata che può influenzare l'insorgenza e la progressione di diverse malattie. Infatti, l'elevata incidenza di malattie cardiovascolari negli anziani è principalmente imputabile al fisiologico rimodellamento cardiaco associato ad un invecchiamento intrinseco. RAGE è un recettore capace di legare diverse molecole e coinvolto in molte malattie legate all'età. La sua isoforma solubile (sRAGE) agisce come un recettore decoy bloccando l'attivazione del recettore legato alla membrana, e suoi livelli circolanti sono stati trovati alterati in diverse patologie croniche ed acute. Il ruolo delle isoforme di RAGE durante l’invecchiamento e, in particolare, nell’invecchiamento cardiaco, non è mai stato studiato. Inoltre, la scoperta di biomarcatori affidabili in grado di valutare lo stato di salute individuale dei soggetti ha importanti applicazioni nel campo della prevenzione, della diagnosi e della gestione della malattia. In tale contesto, lo scopo di questo studio è stato quello di verificare se sRAGE sia un biomarcatore di invecchiamento e di rimodellamento cardiaco legato all’invecchiamento, e valutare il contributo delle isoforme RAGE nell’invecchiamento cardiaco. Risultati: È stato collezionato il siero di soggetti sani, di entrambi i sessi, di età compresa tra i 20 e i 92 anni ed i livelli di sRAGE sono stati valutati mediante ELISA. Abbiamo trovato una significativa diminuzione di sRAGE circolante nei maschi, mentre solo una tendenza nelle femmine. Di conseguenza, abbiamo osservato una forte correlazione di sRAGE con l'età cronologica nei soggetti maschi, ma non nei soggetti di sesso femminile. Topi maschi e femmine a diverse età (2.5-12-22 mesi, Giovani, adulti (MA) e Vecchi, rispettivamente) sono stati sottoposti a ecocardiografia 2D per determinare le dimensioni e la funzione del ventricolo sinistro (LV) durante l'invecchiamento. sRAGE serico diminuisce in maniera simile in entrambi i sessi tra il gruppo Giovani e il gruppo MA, e correla inversamente con le dimensioni e la funzione del LV, in particolare nei machi. Nessuna quantità rilevabile di RAGE è stata trovata nei lisati proteici del LV a tutte le età. Topi Rage-/- hanno mostrato un significativo aumento dei volumi e dei diametri del LV in diastole e in sistole, ed una concomitante diminuzione della frazione di eiezione (EF) e di accorciamento (FS), rispetto agli animali Rage+/+ di pari età durante l'invecchiamento con le più forti differenze presenti tra i gruppi MA. Inoltre, topi MA Rage-/- hanno mostrato la maggiore deposizione di collagene e l’aumento dell'espressione di geni marcatori di scompenso cardiaco (BNP e Ankrd1) rispetto alla controparte Rage+/+. Al contrario, nessuna differenza in termini di dimensioni dei cardiomiociti è stata osservata a qualsiasi età tra i due genotipi. Infine, l’analisi funzionale di annotazione del microarray, basata sull'interazione fra età-genotipo, ha rivelato che la mancanza cronica di RAGE influenza l'espressione di geni associati alla funzione contrattile, al processo di presentazione dell'antigene e dell'immunità adattativa, del pathway dell’insulina, della morte cellulare e dell’apoptosi. Abbiamo anche trovato una correlazione tra i volumi e i diametri del LV in diastole e in sistole e i geni differenzialmente espressi, i quali sono coinvolti in diversi processi come la contrazione muscolare, la fibrosi e la regolazione dell'apoptosi. Conclusioni: I nostri risultati indicano che sRAGE è un biomarcatore serico di invecchiamento sano e di rimodellamento cardiaco legato all'età, preferenzialmente nei maschi. L'assenza di RAGE aggrava l’avverso rimodellamento cardiaco legato all'età. Proponiamo che, tra le isoforme RAGE, sRAGE possa giocare un ruolo fondamentale nell’invecchiamento cardiaco.
Background: Aging is an unavoidable risk factor in later life that can influence the onset and progression of many diseases. In fact, the high incidence of cardiovascular diseases in the elderly is mainly attributable to cardiac remodelling associated to physiological intrinsic aging. RAGE is a multi-ligand receptor involved in many age-related disorders. Its soluble isoform (sRAGE) acts as a decoy receptor being able to block the activation of the membrane-bound receptor, and its circulation levels have been found altered in several chronic and acute pathologies. The role of RAGE isoforms in aging and, in particular, cardiac senescence has never been investigated. Moreover, the finding of reliable biomarkers able to assess individual health status of subjects has important applications in prevention, diagnosis, and disease management. In this context, the aim of this study was to ascertain whether sRAGE is a biomarker of aging and age-related cardiac remodelling, and evaluate the contribution of RAGE isoforms to cardiac aging. Results: Serum of male and female from 20 to 92 years old healthy subjects was collected and sRAGE levels were evaluated by ELISA. We found a significant decrease of circulating sRAGE in males while only a trend in females. Accordingly, we observed a strong correlation of sRAGE with chronological age in male but not in female subjects. Male and female mice at different age (2.5-12-22-months, Young, Middle Age (MA) and Old, respectively) undergone 2D-echocardiography to determine the left ventricle (LV) dimensions and function during aging. Serum sRAGE similarly declines from the Young to the MA group in both sexes, and inversely correlate with LV dimensions and function, preferentially in males. No detectable amount of RAGE protein was found in LV at all ages. Rage-/- mice displayed a significant increase of LV volumes and diameters in diastole and systole, and a concomitant decrease in ejection fraction (EF) and fractional shortening (FS), compared to age-matched wt animals during aging with the strongest differences present between the MA groups. Moreover, MA Rage-/- mice exhibited higher deposition of collagen and expression of heart failure marker genes (BNP and Ankrd1) in respect to the wt counterpart. Conversely, no differences in cardiomyocytes size were observed at any age between the two genotypes. Finally, microarray functional annotation analysis based on the interaction between age-genotype revealed that the chronic lack of RAGE affected the expression of genes associated to contractile fibre function, antigen presenting process and adaptive immunity, insulin pathway, cell death and apoptosis. We also found a correlation between LV volumes and diameters in diastole and systole and differentially expressed genes involved in several processes like muscle contraction, fibrosis, wound healing and regulation of apoptosis. Conclusions: Our results indicate that sRAGE is a serum biomarker of healthy aging and age-related cardiac remodeling, preferentially in males. The absence of RAGE in mice exacerbates adverse cardiac remodeling with age. We propose that, among RAGE isoforms, sRAGE may play a pivotal role in cardiac senescence.

A fase da vida adulta entre 35 e 60 anos, também denominada de meia idade, compreende o período em que os principais sistemas biológicos apresentam importantes declínios funcionais. Nas mulheres, especificamente, é a fase marcada pelo climatério que tem como principal evento a ocorrência da menopausa. Esse evento fisiológico de importância hormonal e reprodutiva está associado em muitas mulheres ao expressivo aumento da prevalência de doenças cardiovasculares, muitas vezes associadas e precedidas por prejuízos na função autonômica cardiovascular. Nesse sentido, a avaliação da funcionalidade autonômica cardíaca é muito importante como conduta para estratificação de risco cardiovascular. De fato, a análise da variabilidade da frequência cardíaca (VFC) é muito utilizada, entretanto a metodologia segue um protocolo padrão que não leva em consideração situações fisiológicas importantes, como é o caso da reorganização da modulação autonômica cardíaca após o estresse induzido pelo exercício. Adicionalmente, a literatura tem optado por ferramentas lineares em detrimento das não lineares na avaliação da VFC. Nesse caso, a proposta do presente estudo foi avaliar e comparar a função autonômica cardíaca em mulheres jovens (GJ: 21 a 30 anos) e de meia idade pósmenopausa (GMI: 45 a 60 anos) por meio da análise linear (análise espectral) e não linear (análise simbólica) da variabilidade da frequência cardíaca em três momentos distintos (em repouso na posição supina, durante o tilt teste e durante o período de recuperação pós teste cardiopulmonar submáximo). O GMI apresentou menores valores de VO2pico (24 ± 1.0 vs 39 ± 1.3 ml.kg. min-1) frequência cardíaca basal (71 ± 2 vs 81 ± 2 bpm) e maiores valores da pressão arterial média (91 ± 2 vs 81 ± 1 mmHg) em relação ao GJ. Também apresentou maior modulação simpática e menor modulação vagal da FC na posição supina, entretanto somente evidenciado pela análise linear. Durante o tilt test as respostas do GMI foram menos proeminentes quando comparado com o GJ. Nesse caso, as avaliações linear e não linear apresentaram resultados semelhantes. Por fim, a análise da VFC durante o período de recuperação mostrou que o GMI apresentou recuperação da modulação autonômica vagal mais rápida evidenciada em ambas análises, linear e não linear. Em conclusão, a avaliação da modulação autonômica cardíaca mostrou que em repouso as mulheres jovens apresentam um predomínio do componente autonômico vagal, enquanto as mulheres de meia idade pós-menopausa apresentam um predomínio simpático. Por sua vez, o tilt test mostrou que a resposta autonômica das mulheres jovens é mais intensa, entretanto na reorganização após o exercício físico as mulheres de meia idade apresentaram maior velocidade no reestabelecimento da modulação vagal. As causas são incertas, porém podem ser decorrentes da redução dos hormônios ovarianos, bem como do processo de envelhecimento por estabelecimento de uma menor complexidade nos sistemas fisiológicos envolvidos.
The stage of adulthood between 35 and 60, also known as middle-aged, covers the period in which the main biological systems have important functional decline. In women, specifically, it is the stage marked by climacteric whose main event the occurrence of menopause. This physiological event of hormonal and reproductive importance is associated in many women to the significant increase in the prevalence of cardiovascular disease, often associated and preceded by losses in cardiovascular autonomic function. In this sense, the evaluation of cardiac autonomic functionality is very important as practice for cardiovascular risk stratification. In fact, the analysis of heart rate variability (HRV) is widely used, however the methodology follows a standard protocol that does not take into account important physiological situations, such as the reorganization of cardiac autonomic modulation after exercise-induced stress. Additionally, the literature has opted for linear tools instead of linear no evaluation of HRV. In this case, the purpose of this study was to evaluate and compare the cardiac autonomic function in young women (GJ: 21 to 30 years) and half postmenopausal age (GMI: 45-60 years) through the linear analysis (spectral analysis ) and non-linear (symbolic analysis) of heart rate variability at three different times (at rest in the supine position during the tilt test and during the recovery period after submaximal cardiopulmonary test). The GMI showed lower values of peak VO2 (24 ± 1.0 vs 39 ± 1.3 ml.kg. min-1) basal heart rate (71 ± 2 vs 81 ± 2 bpm) and higher mean arterial pressure (91 ± 2 vs 81 ± 1 mm Hg) compared to GJ. Also showed higher sympathetic modulation and lower vagal modulation of HF in the supine position, however only evidenced by linear analysis. During the tilt test responses GMI were less prominent compared to GJ. In this case, the linear and nonlinear tools showed similar results. Finally, the analysis of HRV after submaximal cardiopulmonary test showed that the GMI recovered faster autonomic modulation, shown in both analyzes, linear and non-linear. In conclusion, the evaluation of cardiac autonomic modulation showed that resting young women have a predominance of vagal autonomic component, while women half postmenopausal age present a sympathetic predominance. In turn, the tilt test showed that the autonomic response of young women is more intense, but the autonomic reorganization after exercise, the middle-aged women have faster the reestablishment of vagal modulation. The reasons are unknown, but may be due to the reduction in ovarian hormones, as well as the aging process by establishing less complex physiological mechanisms.

Reduction of cardiac myocyte loss and repair of the vasculature post myocardial infarction are important therapeutic goals because the potential for intrinsic repair is limited. Preclinical and limited clinical data support the possibility that bone marrow-derived mesenchymal stem cells may be a suitable cell type for cellular therapy. The goal of this research was to determine the effectiveness of using MSCs from aged mice in cellular therapy for the treatment of AMI. The central hypothesis for this research was that therapeutic potential of mesenchymal stem cells decreases with age. This research utilized global gene expression analysis to investigate molecular differences in MSCs harvested from three different age groups of mice. Microarray analysis was performed to investigate changes in gene expression with respect to aging. Furthermore, both in vitro and in vivo experiments were completed to analyze the functional and molecular characteristics of the MSCs. The data identified age-related defects in mouse MSCs as well as determined the molecular basis for these deficiencies. This study indicates that MSCs from 26m mice are severely deficient in the induction of angiogenesis and cardiac repair due to defective paracrine factor secretion caused by decreased expression of growth factor/cytokine genes. Hypoxia attenuates the deficiency in the aged mice, whereas in young mice low oxygen promotes secretion of paracrine growth factors. It was determined a dysfunction in HIF-1 alpha signaling was present in MSCs from 26m mice and is regulated by the PI3K/Akt signaling in MSCs. Furthermore, two novel and important and novel aspects of this study were the discovery that cell cycle regulation gene expression decreases with age and MSCs have increased insulin resistance with age. Increased insulin resistance in this cell type with aging is likely to have profound effects on the clinical outcomes of using these cells therapeutically. Likewise, loss of cell cycle regulation during proliferation could also lead to undesirable clinical effects. Gaining insight to the repair potential of these cells with respect to age will help to better define future trials of autologous stem cells not only for heart disease but for all of the many applications proposed for these cells.

Age-dependent changes in murine cardiac pacemaker activity. Cardiovascular diseases (CDVs) are the main causes of death. The incidence of morbidity and mortality associated with CDVs increases exponentially in the elderly population due to the increase of both the number of old people and of the average lifespan (for example it is estimated that in the United States there will be 70 million people over the age of 65 by the year 2030, representing almost 25% of the population, 6 . Amongst the age-dependent cardiovascular diseases, the sinoatrial node dysfunction has a primary role 7 ; for this reason, there is a high interest in the study of the pathophysiological mechanisms that are at the basis of cardiac aging. It is known that in humans during ageing there is a decline in maximum heart rate (MHR) and a reduction in the intrinsic heart rate (IHR) 8,9 ; however basal heart rate (BHR) remains the same between the adults and the elderly 10 . We thus decided to better understand the age-associated mechanisms responsible for the changes in intrinsic and maximum heart rate but not in the basal heart rate, and we chose the mouse as a study model. We therefore first confirmed that in our murine model the IHR, but not the basal HR, decreases with ageing; and we also noticed that in adult mice the IHR and the BHR were similar. We focused our studies on the funny current since it is a main contributor to pacemaking generation and modulation and we observed a reduction of the current density and a negative shift of the activation curve in the old animals. We then evaluated the influence of the autonomic system and we found that in adult mice both branches of the autonomic system contribute similarly to HR, though in opposite directions; old mice instead had a lower vagal tone, leading to a reduction in the overall HRV as assessed by spectral analysis, and an increased sympathetic tone, leading to a larger vulnerability to spontaneous arrhythmias compared to adult. Our data highlight that this model recapitulates well the HR features observed in aged humans and can help understanding the mechanisms of the ageing-associated changes in heart chronotropism. The shift of the sympatho-vagal balance toward a sympathetic prevalence in the old animals may explain why, despite the difference in the intrinsic heart rate, the basal heart rate is similar between the two groups. While the current view is that the sympathetic increase is necessary to ensure the homeostatic balance of heart rate during ageing, it is also possible that the age-dependent increase of the sympathetic tone is the cause of the reduction of the intrinsic heart rate which therefore ultimately represents the compensatory effect.
Mode of action of the Traditional Chinese Medicine drug TMYX on pacemaker activity in freely-moving mice and in isolated SAN cells. The identification of novel pharmacological agents able to selectively reduce sinus rate has a strong interest in the clinic because of their potential use in the treatment of ischemic heart disease such as angina pectoris. Despite longstanding and intense investigation, at present there is only one such agent (Ivabradine) that has reached therapeutic application, since all other compounds tested had additional undesired side-effects 11,12 . Our laboratory has started few years ago a collaboration with the University of Tianjin (China) to investigate the efficacy of the cardioactive compound Tongmai Yangxin (TMYX) which is currently used in the Traditional Chinese Medicine as a cardiac regulator 13 . Electrophysiological experiments performed on rabbit SA node cells have shown a dose-dependent slowing effect of TMYX on pacemaking action potential rate. The investigation of the effects of TMYX on the I f current, the major contributor of diastolic depolarization phase, has revealed that at physiological potential the drug exerts a bradycardic action, thus confirming the effect on the spontaneous automaticity observed in SA node cells. During my experimental work, I continued the characterization of the mechanism of action of this Traditional Chinese Medicine drug, working on two parallel aspects: 1) the evaluation of the systemic effect of TMYX and 2) the identification of the molecular mechanisms of the drug. 1) The systemic effect of TMYX was evaluated in freely-moving mice implanted with ECG transmitters. When TMYX was delivered during pharmacological blockade of either sympathetic alone or in combination with parasympathetic block, a deep bradycardia was observed, confirming the in-vitro bradycardic effect. However, quite surprisingly, when the drug was delivered (i.p. injection) during basal heart rate condition, the experiments show an increment of heart rate. 2) Our previous in-vitro experiments had revealed that TMYX acts directly on pacemaker SAN cells and blocks the pacemaker current. We therefore started a series of experiments aiming at the identification of the site of action of TMYX. Our experiments suggest that TMYX shares the modulatory pathway of ACh, but they also exclude that TMYX can bind to the M2 receptor because atropine does not alter the action of TMYX. We then performed inside-out experiments and demonstrated that TMYX does not have any action on the channel when cAMP is either completely absent or it is present at saturating high levels, while TMYX decreases the pacemaker current when cAMP is present at non-saturating levels. Taken together our results demonstrate the presence of at least two molecules that exert different actions: one is a bradycardic agent, whose effect is observed in isolated SAN cells and in the in-vivo model, and the other one is a systemic tachycardic agent, whose effect is observed in the absence of autonomic block. The bradycardic agent appears to behave as an antagonist of the sympathetic stimulation of heart rate. The antagonist action on the sympathetic activity is a key pharmacologic mechanism used by the so-called β-blocker drugs. These drugs are largely used to treat a large number of cardiac diseases including Coronary Artery Disease (CAD) and Heart Failure (HF). However, the often-undesired side effect of β-blockers is a decreased strength of contraction (inotropism) of the heart. According to our data it appears that the active molecule in the TMYX acts directly on the pacemaker channel by antagonizing the stimulating action of cAMP, while β-blockers slow heart rate by decreasing the cAMP levels. This direct antagonistic effect, rather than a block of cAMP production should decrease the heart rate leaving unaltered the strength of contraction. We thus intend to identify and isolate the specific tachycardic/bradycardic molecules since they could have a strong impact in the clinical use.

The aging process is a general event involving all organisms and organs, characterized by physiological and metabolic dysfunctions. In cardiac muscle aging represents the major risk factor for cardiac disease onset. A number of hallmarks characterize the ageing process, nevertheless among those the main is represented by an excessive mitochondrial ROS (radical oxygen species) production. For this reason, it has been hypothesized that ROS lead to mitochondrial DNA (mtDNA) damages, inducing cellular dysfunction and organ failure. Furthermore, mitochondria being responsible for the fine tuning between mitochondrial fusion, fission and autophagy, which are essential processes for cellular functioning, their role in aging become predominant. To understand molecular bases of cardiac muscle aging in a physiological model, the proteomic profiles of Sprague Dawley rat hearts of 6, 22 and 30 months old were analyzed by 2D-DIGE technology (two dimensional Differential In Gel Electrophoresis). To contribute to clarify the role of mitochondria in aging, fusion, fission and autophagy were investigated by antigen antibody reactions on total muscle extracts. In addition, mitochondria were isolated by classical methodologies including differential centrifugation and density gradient for the study of proteomic profile by 2D-DIGE of subsarcolemmal (SSM) and intermiofibrillar (IFM) mitochondria. Results on total cardiac muscle, indicate a number of changed proteins, particularly of specific protein isoforms, even though changes in abundance are modest. These results suggest that this model could be representative of a successful aging, like it occurs in human centenarians. In particular, variations involve myosin binding proteins and the troponin I, mitochondrial aldehyde dehydrogenase (Aldh2) and a group of serpins, suggesting that these proteins could be possible putative biomarkers of the aging process. Concerning mitochondrial dynamic in aging, it is impaired with a decreased fission, an increased fusion and a decreased autophagy. The latter through the increment of LC3, could indicate a protective activation of the non-canonical autophagic process. Furthermore, it has been observed that in course of aging there is an increment of Sirtuin 3, which protects mtDNA from mitochondrial ROS attacks, and of CypD, which promotes the opening of mitochondrial permeability transition pore (mtPTP), with a harmful effect for the cell. The changes, that resulted be protective from senescence are in line with the hypothesis of a successful aging, even though the changes in mitochondrial dynamics are remarkable. However, this study reveals an incoherence between mitochondrial and cardiac tissue proteomic results, particularly on respiratory chain proteins. To avoid unreliable conclusions after proteomics we tested the integrity of isolated mitochondria. We observed that matrix proteins were not enriched in mitochondrial extracts, while the mitochondrial membrane proteins were enriched up to 600%. Further validations were obtained with the analysis of the supernatant (after SS mitochondria enrichment) and by isolation of mitochondria with commercial kits. Our observations are supported by recent papers (Picard et al.), which highlighted the drawbacks of mitochondria isolation by classical methodology demonstrating that the tridimensional mitochondrial network and their interactions with other cellular compartments were destroyed. Also our study underlines technical problems associated with mitochondrial isolation and we suggest, to guarantee results reliability, a careful evaluation of mitochondria integrity (considering both mitochondrial spaces and membranes proteins), before any quantitative differential analysis. The cardiac muscle proteomic changes in this physiological model of aging indicate that some variations are associated to an intrinsic cardiac aging. Further progresses to validate the reliability of proposed biomarkers of aging will be possible by testing them in animal models affected by cardiovascular disorders.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Aging is a complex, dynamic and progressive process characterized by morphological, functional, biochemical, psychological and social age-related changes. These changes occur progressively and lead the individual to gradual reduction of their adaptability and performance skills, making them more vulnerable to intrinsic and extrinsic factors. Resistance training is recommended for elderly people as a promising intervention to prevent or reverse, at least partially, the effects caused by this process. However, the number of studies that address cardiovascular variables behavioral patterns during the recovery period after resistance exercise in the elderly is still limited, despite the potentially useful information that might arise from this observation. In this context, the aim of the present proposal is to analyze the response of the response of heart rate variability (HRV) to resistance exercise during the recovery period (6 minutes) in elderly and young subjects. Volunteers will undergo three visits: 1. ramp type exercise test on a cycle ergometer (clinic avaluation); 2. one maximum repetition (MR) test and 3. A test at an intensity of 70% and 90% of 1RM, on the Leg Press 45º device. The records of the heart frequency (HR) was collected throughout the tests. Our hypothesis is that cardiovascular adjustments, investigated through HRV analysis, will be attenuated in the elderly when compared to young subjects. The results were compared using two-way repeated-measures ANOVA. A significant difference was found between elderly and young during the recovery phase for Mean RR, LF n.u., DFA1 and DFA2. Our findings show that the elderly present higher sympathetic modulation during RE recovery when compared to young subjects, which might be indicative of an attenuated response to exercise in this population.
O envelhecimento é um processo complexo, dinâmico e progressivo, caracterizado por alterações morfológicas, funcionais, bioquímicas, psicológicas e sociais. Tais alterações ocorrem de maneira progressiva e levam o indivíduo à diminuição gradual de sua capacidade de adaptação e desempenho, tornando-o mais vulnerável às agressões intrínsecas e extrínsecas. O treinamento resistido é recomendado para os indivíduos idosos como uma promissora intervenção para prevenir ou reverter, pelo menos parcialmente, as perdas causadas por este processo. No entanto, ainda são limitados os estudos que investigaram o comportamento das variáveis cardiovasculares no período de recuperação pós-esforço em exercício resistido (ER) em idosos, apesar das informações potencialmente úteis que poderiam advir de tal investigação. Neste contexto, a presente proposta terá como objetivo analisar a resposta da variabilidade da frequência cardíaca (VFC) no período de recuperação pós-exercício resistido em indivíduos idosos e jovens. Foram realizadas 3 visitas para realização dos seguintes testes: 1. teste ergométrico do tipo rampa em cicloergômetro (para avaliação clínica); 2. teste de uma repetição máxima (RM) e 3. teste em 70% e 90% do RM no equipamento Leg Press 45º. Os registros dos sinais de frequência cardíaca (FC) foram realizados durante o repouso e no período de recuperação (6 minutos) dos testes de 70% e 90% de 1RM. A hipótese deste estudo é a de que os ajustes cardiovasculares avaliados pela análise da VFC estarão atenuados nos indivíduos idosos quando comparados aos indivíduos jovens. Foi utilizada para análise dos dados ANOVA de medidas repetidas de duas vias. Foram encontradas diferenças significativas entre idosos e jovens durante a fase de recuperação nas seguintes variáveis: média RR, BF u.n., DFA1 e DFA2. Podemos concluir que os idosos apresentam uma modulação simpática com valores mais altos durante a recuperação do que os jovens, podendo ser indicativo de uma resposta atenuada ao exercício nessa população.
CNPq: 450500/2016-0
CNPq: 117515/2014-0
CNPq: 486365/2013-1

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Universidade Federal de Minas Gerais
The thesis consisted of three studies described below. Study I, which aimed to investigate the effect of aging on kinetic responses of heart rate (HR) and oxygen consumption (VO2) during rest-exercise (ontransient) and exercise-recovery transitions (off-transient), and to investigate the influence of exercise intensity (mild and moderate) on the kinetic parameters of these variables. 28 apparently healthy men were evaluated, and 14 constituted the young group (YG) and 14 the elderly group (EG). The evaluation consisted of applying an incremental exercise testing of ramp protocol on cycle-ergometer (IET-R) to determine the maximum power (MP) and discontinuous exercise test on a cycle ergometer (DET-C), which started with an initial power load of 10% of MP with subsequent increase of 10% until exhaustion. Were recorded ventilatory and metabolic variables, the HR and blood lactate at rest and during exercise. The lactate threshold (LT) was closed between the groups (approximately 30% of MP). The EG showed higher values of the kinetic responses, both on and off transitions of HR and VO2 (p<0.05), and the values were higher in moderate compared to mild in YG (p<0.05). We conclude that the elderly have slower kinetic responses of HR and VO2 in relation to young and that at moderate intensity; the kinetic responses were slower in relation to mild intensity in young. Following, the study II aimed to investigate the behavior of the heart rate variability (HRV) responses during a discontinuous resistance exercise (RE) protocol and check whether they agree with the blood lactate responses in the determination of anaerobic threshold (AT) in apparently healthy young and elderly. For this proposal, in the same volunteers in the study I, was applied the test of one repetition maximum (1RM) on the leg press 45º and the discontinuous exercise test on the leg press 45 (DET-L), initiated in 10% of 1RM subsequent increments of 10% until exhaustion, and the HR and blood lactate were obtained at rest and during exercise. The AT was determined at approximately 30% of 1RM in both groups and both methods of analysis (blood lactate and HRV), the HRV index decreased with increasing load and stabilized from the load corresponding to AT in both groups, additionally the blood lactate remained practically stable until the load of AT, and increased significantly after this intensity. The EG had lower HRV values in lower loads of AT, and lower values of HR and blood lactate in loads above of AT in relation to the YG. We conclude that the HRV responses to determine the AT are according to blood lactate, and that the increase in load during the discontinuous RE promoted gradual vagal withdrawal followed by sympathetic activation in both young and the elderly, however, these responses are attenuated with the aging process. Finally, the study III, aimed to determine the AT during discontinuous dynamic and resistance exercise protocol by analyzing blood lactate and HRV in healthy older adults, comparing the cardiovascular, metabolic and autonomic variables between these two exercise modalities. We evaluated the elderly group of individuals during the tests: IET-R, DET-C, 1RM and DET-L. The AT within about 30% of maximum intensity in both the DET-C and DET-L by both methods (blood lactate and HRV). There were no differences in HRV variables between the modalities of exercise and a significant increase in systolic blood pressure and blood lactate after AT load in the DET-L. We conclude that HRV was effective in determining the AT and that the parasympathetic modulation responses were similar between dynamic and resistance exercise.
A tese constou de 3 estudos descritos a seguir. Estudo I, que teve como objetivo investigar o efeito do envelhecimento nas respostas cinéticas da frequência cardíaca (FC) e do consumo de oxigênio (VO2) durante as transições repouso-exercício (fase-on) e exercício-recuperação (fase-off), além de verificar a influência da intensidade do exercício (leve e moderada) sobre os parâmetros cinéticos destas variáveis. 28 homens aparentemente saudáveis foram avaliados, sendo que 14 constituíram o grupo de jovens (GJ) e 14 o grupo de idosos (GI). A avaliação foi constituída da aplicação de um teste de esforço incremental do tipo rampa (TEI-R) em cicloergômetro para determinar a potência máxima (PM) e teste de exercício descontínuo no cicloergômetro (TED-C), sendo este último iniciado com carga inicial de 10% da PM com aumentos subsequentes de 10% até a exaustão. Foram registradas as variáveis ventilatórias e metabólicas, a FC e a lactacidemia em repouso e durante o esforço. O limiar de lactato (LL) foi verificado em cargas relativas similares entre os grupos (aproximadamente em 30% da PM). O GI apresentou maiores valores das respostas cinéticas, tanto na transição on como off da FC e do VO2 (p<0,05), e os valores foram maiores na intensidade moderada em comparação à leve no GJ (p<0,05). Concluímos que os idosos tem respostas cinéticas mais lentas da FC e do VO2 em relação aos jovens e que em intensidade moderada, as respostas cinéticas foram mais lentas em relação à intensidade leve nos jovens. Na sequência, o estudo II objetivou investigar o comportamento das respostas da variabilidade da frequência cardíaca (VFC) durante um protocolo de exercício resistido (ER) descontínuo e verificar se estas são concordantes com as respostas de lactacidemia na determinação do limiar anaeróbio (LA) em jovens e idosos aparentemente saudáveis. Para tal proposta, nos mesmos voluntários do estudo I, foi aplicado o teste de uma repetição máxima (1RM) no leg press 45º e o teste de exercício descontínuo no leg press 45º (TED-L), iniciado em 10% de 1RM com incrementos subsequentes de 10% até a exaustão, sendo a FC e a lactacidemia obtidas no repouso e no exercício. O LA foi determinado em aproximadamente 30% da 1RM em ambos os grupos e em ambos os métodos de análise (lactacidemia e VFC), os índices da VFC diminuíram com aumento da carga e se estabilizaram a partir da carga do LA em ambos os grupos, adicionalmente, a lactacidemia manteve-se praticamente estável até a carga do LA, aumentando significativamente após esta intensidade. O GI apresentou valores reduzidos da VFC nas cargas inferiores ao LA, e valores reduzidos de FC e lactacidemia nas cargas acima do LA, em relação ao GJ. Concluímos que as respostas de VFC para determinar o LA estão de acordo com a lactacidemia, e que o aumento das cargas durante o ER descontínuo, promoveu gradual retirada vagal, seguida pela ativação simpática, tanto nos jovens como nos idosos, no entanto, estas respostas são atenuadas com o processo de envelhecimento. Finalmente o estudo III, teve como objetivo determinar o LA em protocolo de exercício descontínuo dinâmico e resistido por meio da análise da lactacidemia e da VFC em idosos saudáveis, comparando as variáveis cardiovasculares, metabólicas e autonômicas entre estas duas modalidades. Foram avaliados os indivíduos do grupo idoso durante os testes: TEI-R, TED-C, 1RM e TED-L. O LA ocorreu em aproximadamente 30% da intensidade máxima tanto no TED-C como no TED-L, por ambos os métodos (lactacidemia e VFC). Não houve diferenças em relação às variáveis da VFC entre as modalidades de exercício e houve aumento significativo da pressão arterial sistólica e lactacidemia após a carga do LA no TED-L. Concluímos que a VFC foi eficaz na determinação do LA e que as respostas da modulação parassimpática foram semelhantes entre o exercício dinâmico e resistido.

L’obésité et le surpoids ont été décrits comme une pandémie. L’obésité et le vieillissement vont conduire à des complications cardiovasculaires. De plus, l’obésité favoriserait un vieillissement cardiaque prématuré chez les adultes jeunes. L’hypothèse de ce travail est qu’un régime riche en graisses, démarré avant l’âge adulte, poursuivi sur une longue durée, pourrait entraîner un vieillissement « accéléré » cardiovasculaire et métabolique. Nous avons démontré, dans un modèle murin vieillissant, qu’un régime riche en graisses conduit à des troubles métaboliques ainsi qu’à une augmentation de la masse grasse et à une détérioration du métabolisme au niveau du tissu adipeux blanc. Ces troubles sont associés à des altérations au niveau cardiaque, malgré l’absence de modifications de la pression artérielle et de la fréquence cardiaque. Le vieillissement, chez les souris obèses, va conduire à un remodelage du ventricule gauche accompagné par une dysfonction systolique. Au niveau tissulaire cardiaque, le vieillissement et le régime précoce conduisent à l’augmentation de l’expression de gènes de fibrose confirmant ainsi le phénotype hypertrophique. Le vieillissement associé à un régime riche en graisses précoce conduit également à une up-régulation de GDF11. GDF11 peut alors être considéré comme un marqueur de vieillissement cardiaque accéléré. Ces résultats peuvent suggérer des voies thérapeutiques ou préventives, où l’inhibition de GDF11 améliorerait le pronostic et la survie cardiovasculaire des sujets obèses. L’étude de ce modèle nous a ainsi permis de mettre en évidence qu’un régime riche en graisses conduit à un vieillissement accéléré au niveau cardiaque
Obesity and being overweight have been described as a global pandemic. Both obesity and aging will lead to cardiovascular complications. In addition, it has been highlighted that obesity promotes premature cardiac aging in young adults. The hypothesis of this work is that a high fat diet begun before adulthood, pursued over a long period of time, could lead to “accelerated” cardiovascular and metabolic aging. We have demonstrated, in an aging mouse model, that an early high fat diet leads to metabolic disorders and to an increase in fat mass and a deterioration in metabolism of white adipose tissue. These disorders are associated with alterations in cardiac morphology and function, despite an absence of changes in blood pressure and heart rate. Ageing, in obese mice, leads to ventricular remodeling accompanied by systolic dysfunction. In cardiac tissue, aging and early diet lead to an increased expression of fibrosis genes confirming the hypertrophic phenotype. Aging associated with an early high fat diet led also to an up-regulation of GDF11. GDF11 may then be considered as a marker of accelerated cardiac aging. These results may suggest therapeutic or preventive pathways, where inhibition of GDF11 improves prognosis and survival in obese subjects with cardiovascular disease. The study of this model has allowed us to demonstrate that a high fat diet leads to accelerated aging at the level of the heart

The mammalian heart is a remarkable organ in that it must provide for the cardiovascular needs of the organism throughout life, without pausing. Yet, through developmental growth to adulthood and into ageing, the mammalian heart undergoes extensive physiological, morphological and biochemical remodelling. Pivotal to the age-associated alterations in cardiac phenotype is a decline in the proliferative capacity of cardiac myocytes (CMs), which is insufficient to compensate for the basal rate of CM death over time. The terminally differentiated nature of adult CMs also underlies the inability of the heart to repair itself after myocardial damage, such as infarction. As a consequence, existing CMs mount a compensatory hypertrophic response to sustain cardiac output. In parallel, the proliferation rate of resident cardiac fibroblasts, which comprise approximately 60% of total cardiac cells, increases, replacing healthy myocardium with fibrotic scar tissue. Together, CM hypertrophy and fibroblast hyperplasia progressively reduces cardiac function and the ability of the heart to adapt to environmental stressors or damage. Under continued stress or through natural ageing, the heart progresses to a failing state in which cardiac output can no longer meet the demands of the body. The societal impact of ageing-associated decline in cardiac function is great, with heart failure affecting around 8% of over 65s and consuming approximately 2% of the NHS budget. These statistics are set to rise with an ageing population. The substantial phenotypic alterations characteristic of ageing and disease-associated cardiac remodelling requires a wholesale reprogramming of the CM transcriptome. In many biological systems, although yet to be established in adult myocytes, epigenetic mechanisms underlie the transcriptome changes that arise. I hypothesised that alterations in the epigenetic landscape of CMs mediate the transcriptome remodelling that determines the phenotypic transformations that occur in cardiac ageing, hypertrophy and disease. To test this hypothesis, I examined CM-specific changes in DNA cytosine modifications, long non-coding RNA (lncRNA) expression and histone tail lysine methylation marks – epigenetic marks with central roles in transcriptional regulation in many biological systems. I examined how these changes correlate with alterations in the CM transcriptome during disease and ageing. Understanding how alterations in the transcriptome and epigenome contribute to phenotypic changes using whole tissue data is confounded by the heterogeneous nature of the heart, coupled with ageing and disease-associated changes in relative cellular composition. To overcome this, I validated a method to isolate CM nuclei specifically from post-mortem heart tissue. This method also has the advantage that it could be applied to frozen tissue, allowing access to archived material. LncRNAs are functional RNA transcripts longer than 200 bases are emerging as important regulators of gene expression. Common mechanisms of gene expression regulation by lncRNAs include by antisense suppression, as guide/co-factor molecules to direct chromatin modifying components or splicing factors to locations in the genome. Transcriptome profiling in healthy and failing human CMs identified an increase in expression of the lncRNA MALAT-1, which was consistently observed in rodent models of pathology and in ageing. Loss-of-function investigations revealed a potential anti-hypertrophic function for this lncRNA. Specifically, MALAT-1 knock down in vitro in CMs incited spontaneous hypertrophy with features reflecting pathological remodelling in the heart and hypertrophy induced by pro-hypertrophic mediators in vitro. ix In addition, novel uncharacterised transcripts were identified as differentially expressed in cardiovascular disease, including a lncRNA at 4q35.2, which was found significantly downregulated in CMs from human failing hearts. DNA methylation is a stable epigenetic modification and is generally associated with transcriptional repression. It is established by de novo DNA methyltransferases (DNMTs) in early development to determine and maintain differentiated cell states and is ‘copied’ to daughter strands in DNA synthesis by the maintenance DNMT1. Methylcytosine (MeC) can be subject to further processing to hydroxymethylcytosine (hMeC) through a TET protein-mediated oxidation reaction. This serves as a means to actively remove methylation marks as well as hMeC being a novel epigenetic modification in its own right. For the first time, I identified the cardiac myocyte genome as having a high global level of hMeC, comparable with that in neurones. I also discovered an age-associated increase in gene body hMeC that coincided with the loss of proliferative capacity and plasticity of CMs. In parallel, gene body DNA MeC levels decrease in CM ageing. Both these phenomena in gene bodies corresponded with a non-canonical upregulation in expression of genes particularly relevant to cardiac function. This relationship between gene body methylation and transcription rate is strengthened with age in CMs. Recent work in the laboratory had identified the pervasive loss of euchromatic lysine 9 dimethylation on histone 3 (H3K9me2) as a conserved feature of pathological hypertrophy and associated with re-expression of foetal genes. Concurrently, expression and activity of the enzymes responsible for depositing H3K9me2, euchromatic histone lysine methyltransferases 1 and 2 (EHMT1/GLP and EHMT2/G9a) were reduced. Consistently, microRNA-217-induced genetic or pharmacological inactivation of Ehmts was sufficient to promote pathological hypertrophy and foetal gene re-expression, while suppression of this pathway protected from pathological hypertrophy both in vitro and in mice. In summary, I provide new insight into CM-specific epigenetic changes and suggest the epigenome as an important mediator in the loss of plasticity and cardiac health in ageing and disease. Epigenetic mediators and pathways identified as responsible for this remodelling of the CM epigenome suggests opportunities for novel therapy approaches.

Le système cardio-respiratoire joue un rôle prépondérant au sein d’un organisme, en permettant notamment l’apport et la distribution du dioxygène et des nutriments à l’ensemble des cellules. Mieux comprendre les modifications du système cardio-respiratoire au cours de la vie est donc un élément central dans l’évaluation de la capacité de l’organisme à répondre à ses différents besoins énergétiques, ainsi que dans la compréhension du phénomène de mortalité naturelle liée à la sénescence. Cette étude a été réalisée sur un vertébré à durée de vie extrêmement courte (~6 mois), le poisson Nothobranchius furzeri. La température, en plus d’être considérée comme l’un des principaux facteurs environnementaux susceptibles d’influencer la physiologie des téléostéens, est connue pour son effet régulateur sur la longévité. Ainsi, les individus étaient acclimatés à deux températures, 26 °C considérée comme la température optimale chez cette espèce, et une température réduite de 22 °C. Au niveau individuel, les réponses biologiques ont été explorées au travers des performances physiologiques comme mesure indirecte de la fitness : la capacité métabolique aérobie (AS), la croissance, les performances de reproduction, de locomotion et de digestion. A l’échelle sub-individuelle, les mécanismes de régulation de la fonction cardiaque ont été examinés via une étude morpho-fonctionnelle des cardiomyocytes. Les résultats mettent en évidence la présence au cours de la vie de deux phases bien distinctes délimitées par un âge optimal : (1) une première phase d’élévation de l’AS des stades juvénile à adulte ; suivie (2) d’une seconde phase, synonyme de déclin de l’AS, des indicateurs cardiaques et des niveaux d’activités ciblés, associés probablement à l’entrée en sénescence. Une réduction de température accroit la longévité, et retarde les effets néfastes du vieillissement sur l’AS, et les performances cardiaques. Cette étude contribuera à établir une vision globale des effets du vieillissement sur la fonction cardio-respiratoire et à mieux comprendre les mécanismes mis en jeu lors d’un allongement de la longévité par une réduction de la température
Cardio-respiratory system plays a key role in an organism by delivering oxygen and nutrients towards the cells. Exploring its age-dependant changes is therefore a corner stone for assessing the organism capacity to meet its energetic needs along its life cycle, and for the understanding of mechanisms involved in the mortality due to aging process. This study was realized in a vertebrate with an extremely short lifespan (~6 months), the fish Nothobranchius furzeri. Temperature is an external factor that regulates longevity. Here, fish were acclimatized at two temperatures, 26 °C considered as the optimal temperature for this species, and 22 °C. Biological responses of fish were evaluated at individual level through the assessment of aerobic metabolic scope (AS), growth, reproduction, locomotion and digestion, which are considered to be relevant indirect measurement of fitness. Furthermore, mechanisms involved in the cardiac function regulation were explored through a morpho-functional study of cardiomyocytes. Along the individual life cycle, two phases were emphasized: 1) the first corresponds to AS elevation from the juvenile to the adult stages, following by 2) a second phase reflecting the entrance in the senescent stage, characterized by the decline in AS, cardiac performances and in activity level. A temperature reduction increases the individual longevity and slows-down deleterious effect of aging on both AS and cardiac function. This study will contribute to provide a global vision of senescent effects on cardio-respiratory system, and a better understanding of the mechanisms involved in temperature-dependent increase in longevity

La déformation du myocarde quantifiée en imagerie échocardiographique ou en imagerie par résonnance magnétique (IRM) dynamique par traitement d'images conventionnel (suivi de textures), est un marqueur puissant de l'atteinte myocardique, tant il est modifié précocement au cours de la maladie comparé aux marqueurs globaux communément utilisés en routine clinique. Malgré ses performances, son utilisation systématique en routine reste entravée par la complexité et le temps d'analyse nécessaires à l'initialisation manuelle des bords du myocarde.De plus, les logiciels cliniques sont le plus souvent spécifiques au ventricule gauche du cœur, omettant les autres cavités qui sont aussi les cibles de maladies mais ayant une géométrie nettement plus complexe. Dans ce contexte, les objectifs principaux de cette thèse sont : 1) d'évaluer la déformation myocardique par suivi de texture en IRM dans toutes les cavités cardiaques tout en étudiant les effets de l'âge sur les indices estimés, 2) de tirer avantage de ces contours de suivi de texture afin de proposer de nouveaux biomarqueurs quantitatifs de couplage mécano-fonctionnels entres les oreillettes et les ventricules dans le vieillissement en bonne santé, 3) d'évaluer l'effet centre et constructeur sur ces mesures et sur les mesures de strain dérivées par suivi de texture en IRM
Myocardial strain quantified from echocardiography or from cine magnetic resonance imaging (MRI) using conventional image processing (speckle or feature tracking), is a powerful markerof myocardial damage, as it is modified earlier in the course of the disease as compared to global markers commonly used in clinical routine. Despite such performances, its systematic use in routine remains hampered by the complexity and the time-consuming nature of the manual initialization of the myocardial borders. Besides, clinical software is most often specific to the left ventricle, omitting the other chambers which are also targets of diseases but havinga much more complex geometry. In such a context, the main objectives of this thesis are: 1) to evaluate myocardial deformation through MRI feature tracking in all cardiac chambers while studying the effects of age on the estimated indices, 2) to take advantage of feature tracking derived contours in order to design new quantitative biomarkers of mechano-functional coupling between the atria and the ventricles in healthy aging, 3) to evaluate effect of data from different centers and manufacturers on these measurements and on strain measurements derived by feature tracking from cine MRI

In recent years it has become clear that Western societies face a rapidly increasing ageing population. With ageing comes a significant reduction in functional capacity, cardiovascular function, increased cardiovascular disease risk and thus increasing health care costs. Exercise interventions in the elderly may prove to be a valuable tool in coping with an ageing population. It was, therefore, the purpose of this thesis to investigate; a) the effects of healthy ageing upon cardiac structure and function in adult males and females, b) the effects of a progressive aerobic exercise training programme upon cardiac structure and function in post-menopausal females as well as c) the effects of competitive exercise training on cardiac structure and function in post-menopausal female athletes and controls. The exact nature of left ventricular (LV) remodelling with age is the source of some controversy. Within a cross-sectional design cardiac structure and function was assessed in 124 women and 74 men (18-76 years). Left ventricular mass was maintained across the adult age-span in females (r= 0.02, P > 0.05) but was significantly and negatively associated with age in males (r= - 0.36, P < 0.05). The maintenance of LV mass in females despite an age-related decrease in LV volume suggested that remodelling of the LV with age was concentric in nature in females, with a relative wall thickening. In males, however, the large decrease in LV mass along with a smaller decrease in LV volume suggested a form of "eccentric atrophy" of the LV. Other data suggested an increase in male RV volume with age (c. 25%), no depression in LV and RV systolic function with age in either males or females and an expected age-related decrease in LV and RV diastolic filling (E:A ratio). Twenty post-menopausal females completed a progressive 12-month aerobic exercise training programme. Despite a significant and progressive increase in maximal aerobic capacity (pre, 23.7 ± 3.1 ml.kg'l.min"; post, 32.2 ± 4.1 ml.kg'I.min-I) there were few alterations in cardiac structure and function. It seems, therefore, that healthy sedentary females do indeed lose the ability to induce LV hypertrophy (LV mass pre, 155 ± 41 g; post, 136 ± 30 g) with training. There was some evidence of an increase in LV volume with training (and a much smaller trend toward an increase in SV). Other data showed no change with progressive exercise including LV systolic and diastolic function as well as volume data, systolic and diastolic function in the RV. Finally, nine post-menopausal female athletes were compared to an age- and lean body mass-matched control group. In agreement with the intervention study LV mass was not different in the athletes and controls (sedentary, 146 ± 31; active, 143 ± 25 g). To support and extend the training study LV volume (18%) and SV (25%), as well as RV volume (15%), were significantly greater in the athletes than the controls. The athletes also demonstrated an enhanced LV E:A ratio (sedentary 1.12; active, 1.53) although the increase in RV E:A was non significant. Both LV and RV systolic function were not different between groups. In conclusion, there is some evidence that healthy ageing of cardiac structure and function is different in males and females. Further, whilst functional capacity increases with exercise training in post-menopausal women there seems to be a lack of a LV hypertrophic response.

Background Ageing is a risk factor that promotes common cardiovascular diseases such as atrial fibrillation (AF) or heart failure (HF), which in turn are associated with pathological changes in intracellular calcium homeostasis. However, the effects that ageing could have on the calcium homeostasis in human atrial cardiomyocytes are not well known. Furthermore, genetic risk variants at single nucleotide polymorphisms (SNPs) associated with a higher incidence of AF have been identified in the chromosomal region 4q25, close to the locus of the Pitx2 transcription factor that plays an important role in cardiac embryonic development. In the adult heart AF has been associated with changes in the expression of Pitx2, but findings are contradictory and the relationship between the 4q25 risk variants and Pitx2 function remain controversial. Moreover, no functional effects of the 4q25 risk variants on the calcium homeostasis have been identified so far. Therefore, in this thesis we investigated how the two risk factors, ageing and risk variants at 4q25, affect the intracellular calcium homeostasis with the intention of identifying mechanisms that underlie potentially arrhythmogenic changes in the calcium homeostasis caused by these risk factors. Hypothesis Ageing and 4q25 risk variants produce alterations in the intracellular calcium homeostasis in atrial myocytes that alone or in combination contribute to increase the propensity to atrial fibrillation. Aims of the thesis * Analyze the effects of ageing on the mechanisms that regulate the calcium homeostasis in human atrial myocytes. * Use transgenic murine models of ageing to identify molecular mechanisms underlying ageing-dependent changes in the calcium homeostasis. * Investigate how risk variants on chromosome 4q25 associated with increased AF risk, affect electrophysiological characteristics of human atrial myocytes and to identify underlying molecular mechanisms. * Investigate how ageing modulates the effects of 4q25 risk variants in human atrial myocytes. Methods Experiments were performed on isolated atrial or ventricular cells from human or murine models. Electrophysiological data were obtained using patch- clamp techniques and confocal microscopy. RT-PCR and western blot techniques were used to determine the expression levels of mRNA and the proteins studied. Results The results described in this thesis show that aging decreases the amplitude of the calcium current (ICa), an electrophysiological parameter that is also reduced by AF, the calcium content of the sarcoplasmic reticulum (SR), and the global calcium transient. These findings are corroborated by comparable changes in the expression of the proteins undertaking the corresponding calcium transport or buffering. Together, these changes likely reduce atrial contraction in the elderly. The results were reproduced in an animal model of premature aging (Zmpste24-/-) with defective lamin processing, reinforcing the notion that this mechanism may, at least partially, underlie the observed effects of aging on the calcium homeostasis in human atrial myocytes. In addition, ageing accentuated some of the effects of ageing on calcium handling in patients with a previous history of AF. Of particular interest, the ICa amplitude was further depressed by aging in patients with AF, which might contribute to maintain atrial arrhythmic episodes in these patients. The study of risk variants on chromosome 4q25 shows that the presence of the rs13143308T risk variant, alone or together with the risk variant rs2200733T, was associated with a higher frequency of spontaneous calcium release, transient inward currents (ITI) and membrane depolarizations, typical of AF. These results are the first to provide an electrophysiological mechanism that could explain a higher incidence of AF in individuals carrying risk variants at 4q25. Moreover, electrophysiological studies in right atrial myocytes from a mouse model with atrial Pitx2 insufficiency (NppaCre+Pitx2fl/-) reproduces all alterations in calcium homeostasis observed in patients with 4q25 risk variants. These results support the notion that modulation of the intracellular calcium handling by Pitx2 plays an important role in electrophysiological processes associated with AF. Analysis of potential synergies between risk variants at 4q25, ageing, and AF revealed that several effects of ageing were accentuated in patients with AF whereas aging per se does not modify the effects of the 4q25 risk variants on calcium homeostasis. However, as aging reduces the amplitude of ICa, which would reduce the atrial refractory period, this could prolong the duration of atrial arrhythmic episodes favored by the higher frequency and amplitude of spontaneous membrane depolarizations in carriers of 4q25 risk variants. Conclusions Ageing modulates calcium homeostasis in human atrial myocytes by decreasing ICa, calcium transient and SR calcium load. These changes are reproduced in a progeric mouse model, favoring a progressive decline of contractile function with age. Moreover, the observed ICa reduction is a characteristic feature of AF that may favor its maintenance in elder patients. Risk variants located on the chromosomal region 4q25, specifically the variant rs13143308T, alone or together with rs2200733T, increases spontaneous calcium release, ITIs, and membrane depolarizations. These changes are reproduced in a mouse model of Pitx2 insufficiency, and are all hallmarks of AF that could favor the initiation of arrhythmic events in carriers of the risk variants. The combined effects of 4q25 risk variants and ageing may work synergistically to promote atrial arrhythmia, with the former constituting an arrhythmogenic electrophysiological substrate that favor initiation of atrial arrhythmic episodes, and with ageing favoring their maintenance.
Antecedentes El envejecimiento es un factor de riesgo que favorece enfermedades cardiovasculares comunes como la fibrilación auricular (FA) o la insuficiencia cardíaca (IC), que a la vez se asocian a cambios patológicos en la homeostasis intracelular de calcio. Sin embargo, no se conocen los efectos que el envejecimiento puede tener sobre los mecanismos de la homeostasis del calcio en cardiomiocitos auriculares humanos. Por otro lado, se han descrito variantes de riesgo genéticas asociadas a la FA en la región cromosómica 4q25, próximas al factor de transcripción Pitx2 que tiene un papel importante en el desarrollo cardíaco embrionario. En el corazón adulto Pitx2 se ha asociado a predisposición a arritmias auriculares, pero la relación que existe entre los variantes de 4q25 y la función de Pitx2 es controvertida. Además, se desconocen los efectos que los variantes de riesgo 4q25 tienen sobre la homeostasis del calcio. Por ello, en esta tesis se han investigado los mecanismos que pueden subyacer a los dos factores de riesgo envejecimiento y variantes de riesgo en 4q25. Hipótesis El envejecimiento y las variantes de riesgo en 4q25 producen alteraciones en la homeostasis del calcio intracelular en miocitos auriculares, que por sí solas o en combinación contribuyen a aumentar la propensión a la fibrilación auricular. Objetivos * Analizar los efectos del envejecimiento en los mecanismos que regulan la homeostasis del calcio en miocitos auriculares humanos. * Utilizar modelos murinos transgénicos de envejecimiento para identificar los mecanismos moleculares que subyacen a los cambios en la homeostasis del calcio debido al envejecimiento. * Investigar cómo las variantes de riesgo en el cromosoma 4q25 asociadas con un mayor riesgo de FA, afectan a las características electrofisiológicas de los miocitos auriculares humanos e identificar los mecanismos moleculares subyacentes. * Investigar como la edad modula los efectos de las variantes de riesgo en 4q25 en miocitos auriculares humanos. Métodos Los experimentos se llevaron a cabo en células auriculares o ventriculares aisladas de humano o de los distintos modelos murinos. Mediante las técnicas de patch-clamp y microscopía confocal se obtuvieron los datos electrofisiológicos. Las técnicas de RT-PCR y western blot se usaron para determinar los niveles de las proteínas estudiadas. Resultados Los resultados de esta tesis muestran que el envejecimiento disminuye la corriente de calcio (ICa), parámetro electrofisiológico que también está reducido en la FA, así como del contenido de calcio del retículo sarcoplásmico (RS), del calcio transitorio global y de las principales proteínas reguladoras del calcio, lo que conjuntamente podría reducir la contracción auricular en los ancianos. Estos resultados fueron reproducidos en modelo animal de envejecimiento prematuro (Zmpste24-/-) que no procesan correctamente la proteína lamina, reforzando la noción que este mecanismo podría subyacer a los efectos del envejecimiento sobre la homeostasis del calcio en las miocitos cardíacos. Además se encontró que en pacientes con previa historia de FA, el envejecimiento tenía un efecto sumatorio sobre algunos efectos deteriorantes de la FA sobre el manejo de calcio, acentuando así a disminución de la ICa con la edad. El estudio de las variantes de riesgo en el cromosoma 4q25 muestra que la variante de riesgo rs13143308T por sí sola o junto con rs2200733T están asociadas a alteraciones electrofisiológicas típicas de la FA. Así, miocitos de pacientes portadores de estas variantes tenían una mayor frecuencia de liberación espontánea de calcio, corrientes de entrada transitorias (ITIs) y despolarizaciones de membrana espontaneas. Estos resultados son los primeros en proporcionar un mecanismo electrofisiológico que podría explicar la mayor incidencia de FA en individuos con variantes de riesgo en 4q25. Estudios electrofisiológicos en miocitos auriculares de un modelo de ratón con deficiencia auricular de Pitx2 (NppaCre+Pitx2fl/-) reproduce todas las alteraciones en la homeostasis del calcio observados en pacientes con variantes de riesgo 4q25. Estos resultados avalan la noción de que la modulación del calcio intracelular por Pitx2 juega un papel importante en procesos electrofisiológicos asociados a la FA. El análisis de potenciales efectos sinérgicos entre variantes de riesgo en 4q25, envejecimiento y la FA revelaba que el envejecimiento per se no modifica los efectos que tiene las variantes 4q25 sobre la homeostasis del calcio. Sin embargo, dado que el envejecimiento reduce la amplitud de la ICa, lo cual reduciría el periodo refractario auricular, podría favorecer la prolongación o el mantenimiento de episodios de arritmia inducidas por actividad eléctrica espontanea. Por lo tanto, es posible que las variantes de riesgo 4q25 constituyan un sustrato electrofisiológico arritmogénico que favorece el inicio de episodios arrítmicos auriculares, y que el envejecimiento actúe prolongando la duración de estos episodios al reducir el periodo refractario auricular a través de la reducción de la amplitud de la ICa. Conclusiones El envejecimiento modula la homeostasis del calcio en miocitos auriculares humanos mediante la disminución de la Ica, del calcio transitorio y del calcio acumulado en el RS. Estos cambios favorecen por un lado el deterioro progresivo de la función contráctil con la edad, y por otro el acortamiento del período refractario mediado por la reducción de la amplitud de la ICa. El modelo murino Zmpste24-/- reproduce los efectos observados reforzando el mecanismo propuesto. Las variantes de riesgo localizadas en la región cromosómica 4q25, concretamente rs13143308 por sí sola o junto con rs2200733, aumentan la liberación espontánea de calcio, ITI y despolarizaciones de la membrana, parámetros característicos de la FA, pudiendo originar eventos arrítmicos en pacientes portadores de las variantes de riesgo. El modelo murino con deficiencia parcial de Pitx2 (NppaCre+Pitx2fl/-) reproduce lo observado en humanos portadores de las variantes de riesgo, reforzando la idea de Pitx2 como nexo entre las variantes de riesgo 4q25 y las alteraciones que provocan en la homeostasis del calcio. La combinación de los efectos encontrados en este estudio propondría a las variantes de riesgo en 4q25 como un substrato arritmogénico que favorece la iniciación de episodios arrítmicos y al envejecimiento como factor que los prolongaría debido a la reducción del período refractario producido por la reducción de la amplitud de la ICa.

Orientador: Vera Aparecida Madruga Forti
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Fisica
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Resumo: O objetivo deste estudo foi analisar e comparar a magnitude das respostas cardiovasculares de mulheres na pós-menopausa sedentárias e treinadas durante as condições de vigília em repouso (VIG) e sono (SONO) a partir do estudo da variabilidade da freqüência cardíaca (VFC). Foram estudas 15 mulheres pós-menopausadas, todas as usuárias de Terapia de Reposição Hormonal (TRH) consideradas clinicamente saudáveis que foram divididas em dois grupos distintos: 6 sedentárias (SED) e 9 fisicamente treinadas há pelo menos doze meses (TRE). Inicialmente as voluntárias foram submetidas a uma anamnese para sua caracterização individual e verificação dos critérios de inclusão e exclusão do grupo estudado. Em seguida, as mulheres pósmenopausadas selecionadas passaram por avaliações: antropométrica e clínica (ginecológica e cardiológica) para afastar a possibilidade de patologias que pudessem interferir nos resultados do presente estudo. Foram coletados os dados referentes ao comportamento autonômico da freqüência cardíaca nas condições de vigília em repouso e sono através da eletrocardiografia dinâmica (HOLTER) de 24 horas e tais dados foram utilizados para a análise da VFC nos domínios do tempo (DT) e da freqüência (DF). A análise da VFC no DT incluiu a média dos intervalos RR (iRR) e seu desvio padrão (DPiRR), enquanto no DF foram estudados os componentes espectrais de baixa (BF: 0,04 ¿ 0,15 Hz) e alta freqüência (AF: 0,15 ¿ 0,40), e a relação BF/AF. Diferenças estatisticamente significantes foram aceitas quando os intervalos de confiança da mediana não se sobrepuseram (p<0,05). Quando comparados os valores medianos dos grupos (SED=73,7 e TRE=64,4bpm) constatamos que a variável Média da FCVIG foi estatisticamente inferior para o grupo TRE (p<0,05). Já para a variável Média da FCSONO (SED=65,5 e TRE=56,2bpm), os valores não atingiram diferença estatisticamente significativa entre os grupos. Para a Média iRR tanto na condição de vigília quanto no sono, as diferenças entre os valores encontrados (SED=749,28 e TRE=916,88ms) e (SED=859,84 e TRE=1059,31ms) foram estatisticamente inferiores (p<0,05) para o grupo SED quando comparados ao grupo TRE. Não houve diferenças estatisticamente significativas entre os grupos para as variáveis DPiRR, BF, AF e BF/AF em nenhuma das condições estudadas (VIG e SONO)
Abstract: The aim of this survey was to analyze and compare the magnitude of the cardiac autonomic activity of women in the one after menopause during the conditions of vigil in rest (VIG) and sleep (SLEEP) through heart rate variability (HRV). Fifteen postmenopausal women were studied, all of them users of Hormone Replacement Therapy (HRT) considered clinically healthy that were divided in two distinct groups: six sedentary and nine physically trained in a regular and extended way, over twelve months. Firstly the volunteers were submitted to anamneses with the aim of gathering necessary information to include the volunteers in the research. Then the selected status postmenopausal women went through some evaluations: anthropometrics and clinical (gynecological and cardiological) to evaluate the physical conditions and drive away the possibility of pathologies that could interfere in the results of the present survey. The referential data were gathered to the heart rate autonomic behavior in the conditions of vigil in rest and sleep through a 24-h dynamic electrocardiography (HOLTER) and such data were used for the analysis of HRV parameters in time (TD) and frequency (FD) domains. HRV analysis in TD included mean RR interval length (iRR) and its standard deviation (SDNN), while in FD, low frequency (LF: 0,04 ¿ 0,15 Hz) and high frequency (HF: 0,15 ¿ 0,40 Hz) spectral components and the LF/HF ratio were analyzed. Statistical significance was accepted when median confidence intervals did not overlap for p< 0,05. When compared the group values (73,7 and 64,4) for the HRVIG variable, we verified that the difference was statically meaningful (p< 0,05). As for the HRSLEEP (65,5 and 56,2), there was no statistical meaningful difference between the groups. For the Mean iRR in the vigil and sleep conditions the differences between the found values (749,28 and 916,88) and (859,84 and 1059,31) were much lower (p< 0,05) for the sedentary group when compared to the physically trained group. There were no differences with statistical meaning between the groups for the variables SDNN, LF, HF and LF/HF in any of the conditions (vigil and sleep)
Mestrado
Mestre em Educação Física

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PROQUALI (UFJF)
Com a mudança ao longo dos dois últimos anos do perfil de morbimortalidade da população idosa, a doença cardiovascular representa hoje, no Brasil, a maior causa de morte. Existem estudos sobre a insuficiência cardíaca no idoso com enfoque na área biológica, porém há escassez de trabalhos que abordem o problema pela ótica do próprio idoso doente. Assim objetivamos estudar os significados de ser portador de insuficiência cardíaca sob a ótica de pacientes idosos. Trata-se de um estudo que empregou a metodologia clínico-qualitativa. Os sujeitos foram idosos a partir de 60 anos de idade, com insuficiência cardíaca, atendidos em dois hospitais. Utilizamos as técnicas de entrevista não dirigida e observação participante para coletar dados e o método de análise de conteúdo para analisá-los. Para ancorar esta pesquisa, o referencial teórico utilizado foram os estudos desenvolvidos por Perestrello e a psicossomática de Mello Filho. Participaram da pesquisa 11 idosos. Após as análises, emergiram duas categorias: “O Significado de estar com insuficiência cardíaca”, com as subcategorias: 1. O sentido iminente da morte e o medo de morrer. 2. Do desamparo vivido ao amparo familiar. 3. Aspectos emocionais que antecedem a cirurgia e a necessidade de comunicação; e a segunda categoria “Tratamento recebido durante a hospitalizado”, com a subcategoria: 1. Cuidado humanizado num hospital, 2. Equipe multidisciplinar e comunicação. Percebemos que por estarem doentes e terem que passar por cirurgia cardíaca, surgiram emoções que os colocaram em uma condição de limitação, tanto física como mentalmente que lhes causou tristeza, medo de morrer e angústia pelo desconhecido. Pudemos observar que a comunicação, quando não estabelecida de forma adequada e clara, não facilita o entendimento do paciente ao que lhe é dito, deixando-o com medo e ansioso, a ponto de fazê-lo desistir do tratamento. No que tange à forma como foram tratados pelos profissionais no hospital, no período de internação, os idosos relataram respeito, zelo e carinho, além de postura alegre, atenção, dedicação de alguns minutos de conversa e educação no convívio com eles. Destaca-se como resultado importante e curioso o fato de não necessariamente apresentarem extrema preocupação por estarem fisicamente incapacitados devido à doença ou por serem idosos, mas com o fato de que a morte os afastaria do convívio com seus familiares. Trata-se de um sentimento inverso de perda, uma vez que demonstram subliminarmente a necessidade de afeto imediato dos seus familiares. Os idosos do estudo têm espírito jovem e objetivos para as suas vidas. Assim sendo, concluímos que deve ser aperfeiçoada a comunicação dos profissionais de saúde com o idoso portador de insuficiência cardíaca, por meio do ensino de técnicas que os auxiliem a manter um canal de comunicação mais efetivo. Torna-se importante a manutenção do acolhimento, percebido nas falas dos pacientes, quando se referem à equipe de saúde, e a capacitação da equipe de enfermagem para um cuidado humanizado. Fundamental também que o trabalho multiprofissional seja cada vez mais uma realidade.
Over the past two years following some shifts in the morbidity and mortality profile of the elderly population, cardiovascular disease is currently the leading cause of death in Brazil. There are a number of studies focusing heart failure among the elderly specifically in the biological area, but there seems to be a lack of research approaching the subject from the perspective of the elderly patient himself/herself. Thus our purpose is to investigate the meanings of being a patient with heart failure considering the older population. This is a study using the clinical-qualitative methodology among elderly people aged over 60 suffering from heart failure assisted in two hospitals. Non-directive interviews, participant observation and the method of content analysis were used to collect data and analyze them. As a theoretical framework the studies carried out by Perestrello as well as Mello Filho psychosomatics approach were used. Eleven elderly participants joined the research. Following the analysis, two categories have emerged: "The Meaning of being a heart failure patient", with some subcategories: 1. The sense of our impeding death and the fear of dying. 2. From experiences of helplessness to family support. 3. Emotional Aspects arising before the surgery and the need for Communication; and the second category: "Treatment provided by the health team to the hospitalized patient" with the subcategory: 1. Treatment for hospitalized elderly: care with humanization, multidisciplinary teamwork and communication. As a result, it was observed that due to the fact that they are ill and facing the need to undergo a cardiovascular surgery some emotions came to the surface creating conditions of physical and mental limitation which may be the cause of sadness, fear of death and anguish of the unknown. We could note that when communication does not happen properly or clearly, the understanding process becomes more difficult for the patient, causing fear, anxiety and even a wish to abandon treatment. The patients’ experience about how they were treated during the hospitalization period involves respect, caring and affection delivered by nursing technicians, registered nurse, physician, cleaning and catering service employees. They spent time with professionals who maintained a positive attitude, providing attention, talking to them and demonstrating politeness during the interaction. As an interesting finding we may remark that they express deep concern not about being physically disabled because of the disease or advanced age, but rather due to the fact that if they die they will no longer be among their families which constitutes a backward sense of loss. Besides they demonstrate an underlying need to get more affection from family members and fell mentally renewed, ready to reach goals in life. We conclude therefore that communication with the patient should be improved by means of teaching techniques that enable professionals to keep a more effective communication channel open with regard to the understanding of illness and treatment in elderly heart failure patients. It becomes relevant to make patients feel cared, as it was mentioned by them approaching the health team, and prepare the nursing team to provide humanized care allowing multiprofessional teamwork to be increasingly feasible.

Sabe-se que o sistema imune, através de um fenômeno denominado imunossenescência, gradativamente diminui a sua capacidade de resposta durante a vida. Este fato pode tornar o indivíduo mais suscetível a infecções e outras patologias. Neste contexto, seria útil procurar por fatores que alterassem esta evolução natural, principalmente os capazes de acelerar este processo. Por esta razão, nós procuramos por diferenças nos parâmetros imunológicos entre o antes e o depois da cirurgia de valva cardíaca em idosos com mais de 65 anos. Nossos resultados não apontaram, no pós-operatório, para uma diminuição da capacidade imune, uma vez que os testes cutâneos de hipersensibilidade para o PPD, tricofitina e candidina não se alteraram. Quando a resposta linfoproliferativa foi avaliada in vitro, também não apresentou diferença. Por outro lado, nós observamos um aumento na porcentagem de células T CD3 +, T CD4 + e monócitos no sangue periférico, quando comparamos os períodos. Sendo que os marcadores de ativação cellular CD25 +, CD69 + e o CD95 também se apresentaram elevados. Quanto a secreção de citocinas, nossos resultados apontam para um amento de IL-4 e IL-8. Inversamente, concentrações reduzidas de IL-2, IL-12 e IFN- foram detectadas no sobrenadante de PBMCs quando estimuladas in vitro. Em suma, nossos dados demonstram que a cirurgia de valva cardiaca é capaz de alterar vários parâmetros da resposta immune, com um aumenrto da porcentagem de células, quanto da expressão de marcadores de ativação celular e secreção de citocinas
It is known that the immune system, through a phenomenon called immunosenescence, undergoes functional changes during life which may culminate in a diminished capacity of response, turning the subject more susceptible to infections and other pathologies. In this context, it is useful to search for factors that alter this natural evolution, mainly able to delay this process. For this reason, we assessed different immunologic parameters before and after cardiac valve surgery in 65 year-old patients. Our results did not point to a postoperative immunedeficiency-like state, once that the cutaneous tests to PPD, candidin and tricophytin remained positive for most of the subjects. When the proliferative response was assessed in vitro, there were also no differences. On the other hand, we observed a post-surgical increase in the percentage of T CD3 +, T CD4 + cells and in monocytes from peripheral blood when we compare both periods. Moreover, it is important to highlight that activation markers, such as CD25, CD69 and CD95 were also presented in higher levels. According to the cytokine secretion, our results appointed to a greater secretion of IL-4 and IL-8 postoperative. Conversely, reduced concentrations of IL-2, IL-12 and IFN- were detected in supernatant of PBMCs when stimulated in vitro. In summary, our data reveal that the cardiac valve surgery with extra corporeal procedure and anesthesia is able to alter several parameters of the immune response, with an increased percentage of the major assessed cells, as well as in the expression of activation markers and cytokine secretion

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O treinamento muscular inspiratório promove efeitos crônicos positivos sobre variáveis fisiológicas em diferentes populações, incluindo idosos. No entanto, o conhecimento dos efeitos agudos cardiovasculares promovidos pelo exercício muscular inspiratório (EMI) ainda é escasso. Considerando-se que o envelhecimento fisiológico prejudica a modulação autonômica cardíaca e que esta é visivelmente afetada pela respiração, torna-se relevante investigar as respostas aguda e tardia de uma sessão de EMI sobre o controle autonômico dos batimentos cardíacos em idosos. Para isso, quinze idosos não tabagistas e sedentários, foram submetidos aleatoriamente à duas sessões de exercício: EMI de moderada intensidade (40% da pressão inspiratória máxima) e Sham (sem carga resistiva). A modulação autonômica cardíaca foi avaliada pelas seguintes medidas de variabilidade da frequência cardíaca (VFC) calculadas nos domínios do tempo e da frequência: duração média dos intervalos R-R normais (MNN), desvio padrão dos intervalos R-R normais (SDNN), raiz média quadrática da diferença entre intervalos R-R normais sucessivos (RMSSD), potências espectrais de baixa (LF) e alta frequência (HF), em unidades absolutas (ms2) e normalizadas (u.n.), e razão LF/HF. O efeito agudo foi estudado pela comparação das medidas de VFC obtidas a partir do sinal do eletrocardiograma (ECG) de curta duração na condição basal (antes do exercício) e na recuperação por uma hora pósexercício (Rec 1 = 10’- 15’; Rec 2 = 25’- 30’; Rec 3 = 40’- 45’e Rec 4 = 55’- 60’). O efeito tardio foi investigado pela análise das medidas de VFC obtidas pelo sinal do ECG de longa duração, coletado por equipamento de monitorização ambulatorial, comparando cada hora após a colocação do aparelho em relação à primeira hora, e também os períodos de vigília-noite (18:00 às 21:00), sono (00:00 às 05:00) e vigília-dia (08:00 às 14:00), determinados pelos registros nos diários dos participantes. O teste de análise de variância de duas entradas para medidas repetidas, seguido do post hoc de Tukey, foi empregado para todas as comparações, sendo considerado nível de significância α = 5%. Adicionalmente, foi calculado o tamanho do efeito (d de Cohen) para avaliação da magnitude do efeito agudo observado em cada sessão de exercício. Agudamente houve aumento significativo do MNN (P <0,001) durante toda a recuperação. Além disso, as medidas SDNN (P = 0,01), RMSSD (P <0,001) e as potências espectrais LF (ms2) (P < 0,001) e HF (ms2) (P < 0,001) aumentaram significativamente a partir da Rec 2 em comparação ao basal. Não foram encontradas diferenças para as demais medidas, bem como entre as sessões de exercício para nenhuma variável. A análise do d de Cohen mostrou que a carga moderada potencializou o efeito agudo observado nas medidas de VFC. De forma tardia, as intervenções não promoveram efeitos significativos na modulação autonômica cardíaca, já que as alterações observadas ao longo das horas subsequentes às sessões de exercício e nos períodos de sono e vigílias relacionam-se às mudanças inerentes ao ritmo circadiano: aumento de medidas que refletem a modulação vagal durante o sono. Assim, concluiu-se que uma sessão EMI de moderada intensidade promove melhora aguda da modulação autonômica cardíaca e não gera efeitos tardios significativos nas medidas de VFC em idosos.
Inspiratory muscle training promotes positive chronic effects on physiological variables in different populations, including the elderly. However, knowledge is scarce in relation to the acute cardiovascular effects promoted by the inspiratory muscle exercise (IME). Considering that physiological aging impairs cardiac autonomic modulation and that it is noticeably affected by breathing, it becomes relevant to investigate the acute and late responses of a single IME session on the autonomic control of the heart beats in elderly. Fifteen non-smokers and sedentary elderly were randomly assigned to two exercise sessions: moderate intensity IME (40% maximal inspiratory pressure) and Sham (no resistive load). Cardiac autonomic modulation was assessed by the following measures of heart rate variability (HRV) calculated in time and frequency domains: mean duration of normal RR intervals (MNN), standard deviation of normal RR intervals (SDNN), root of the mean square differences of successive normal RR intervals (RMSSD), power of the spectral bands of low (LF) and high (HF) frequencies in absolute (ms2) and normalized (n.u.) units, and LF/HF ratio. The acute effect was studied by comparing the HRV measures obtained from the short-term electrocardiogram (ECG) signal at baseline (before exercise) and for one hour post-exercise recovery (Rec 1 = 10’- 15’; Rec 2 = 25’- 30’; Rec 3 = 40’- 45’and Rec 4 = 55’- 60’). The late effect was investigated by the analysis of the HRV measures obtained from the long-term ECG signal, collected continuously by ambulatory monitoring equipment, comparing every hour after the device was placed in relation to the first hour, and also between the periods wake-night (18:00 to 21:00), sleep (00:00 to 05:00) and wake-day (08:00 to 14:00), determined by the participant’s records. The two-factor analysis of variance with repeated measures was used for all comparisons, followed by Tukey's post hoc, and significance level α = 95% was considered. In addition, the effect size (Cohen's d) was calculated to assess the magnitude of the acute effect observed in each exercise session. There was a significant increase in MNN (P <0.001) throughout the recovery. In addition, SDNN (P = 0.01) and RMSSD (P <0.001) measures and LF (ms2) (P <0.001) and HF (ms2) (P <0.001) spectral bands increased significantly from Rec 2 compared to baseline. No differences were found for the other HRV measures, as well as between the exercise sessions for neither variable. The analysis of Cohen's d showed that the moderate load potentiated the acute effect observed in HRV measures. Late, interventions did not promote significant effects on cardiac autonomic modulation, since the changes observed during the hours following the exercise sessions and in the sleep and wake periods are related to the changes inherent to the circadian rhythm: increase of measures that reflect vagal modulation during sleep. Thus, it was concluded that a single moderate-intensity IME session promotes an acute improvement in cardiac autonomic modulation and does not generate significant late effects on HRV measures in elderly men.

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Background: Frailty is a critical state of physiological complexity loss. Evaluation measures of complexity could contribute for a better comprehension regarding the frailty process. Objective: to evaluate complexity of HRV, at rest and after postural change, on frailty syndrome. Design: cross-sectional. Setting: community. Subjects: 100 individuals over 60 years old, distributed in groups according to the frailty phenotype: frail (n=8), pre-frail (n=46) and non-frail (n=46). Methods: The electrocardiogram was made in supine and orthostatic postures, for 10 minutes in each position. Sequences of 256 RR intervals were analyzed through linear (spectral analysis low frequency in normalized units (LFnu) and high frequency in absolute units (HFabs)) and non-linear methods (symbolic analysis 0V% and 2UV%, Shannon entropy (SE), conditional entropy (normalized complexity index NCI)). Results: The NCI did not show difference among the evaluated groups in rest supine, however NCI presented reduced values in all 3 groups after orthostatic challenge. Except AFabs, other indices did not differ between groups at rest supine. Conclusion: The results of this study indicate that there is no decrease of complexity on frailty syndrome, possibly because it already presents decreased values with the senescence. The postural change was unable to detect any impairment in HRV complexity associated with the frailty process.
A fragilidade é um estado crítico de perda da complexidade fisiológica, que resulta em maior vulnerabilidade. Medidas de avaliação da complexidade poderiam contribuir para melhor compreensão sobre o processo de fragilização. Objetivo: avaliar a complexidade da variabilidade da frequência cardíaca (VFC), em repouso e após mudança postural, na síndrome da fragilidade. Desenho experimental: estudo transversal. Ambiente de pesquisa: comunidade. Sujeitos: 100 idosos maiores de 60 anos, divididos em grupos, segundo o fenótipo da fragilidade: frágil (n=8), pré-frágil (n=46) e não-frágil (n=46). Métodos: O eletrocardiograma foi coletado na postura supina e ortostática, por 10 minutos em cada posição. Trechos de 256 intervalos RR foram analisados por metodologias lineares (análise espectral baixa frequência em unidades normalizadas (BFun) e alta frequência em unidades absolutas (AFabs)), bem como não lineares (análise simbólica - 0V% e 2VD%, entropia de Shannon (ES), entropia condicional (índice de complexidade normalizado - ICN)). Resultados: o ICN não apresentou diferenças entre os grupos avaliados, no entanto teve seus valores reduzidos em todos os grupos após a mudança postural. Com exceção da AFabs, os demais índices não diferiram entre os grupos, na condição de repouso supino. Conclusão: Os resultados deste estudo indicam que não há redução da complexidade na síndrome da fragilidade, possivelmente pelo fato desta já apresentar valores reduzidos na senescência. A resposta da complexidade cardíaca à mudança postural não apresentou diferenças na presença da síndrome da fragilidade.

Estudou-se o efeito do treinamento físico sobre a freqüência cardíaca (FC), a freqüência cardíaca intrínseca (FCI), o efeito vagal (EV), o tônus vagal (TV), o efeito simpático (ES) e o tônus simpático (TS), de ratos idosos em repouso volitivo, na esteira, e durante o exercício de intensidade progressiva (4 estágios de 5 min à 5; 7,5; 10 e 15 m.min-1). Verificaram-se, também, as respostas da FC à doses crescentes de agonistas ?-adrenérgico (isoproterenol) e muscarínico (metacolina). Utilizaram-se 20 ratos Wistar machos, aleatoriamente divididos em dois grupos: Treinado (T, 28+2 meses, 460+36 g), submetido a 10 semanas de treinamento físico de moderada intensidade; e Sedentário-controle (S, 28+2 meses, 461+43 g), apenas manipulado, três a cinco vezes por semana, durante nove semanas, e submetido a cinco minutos de exercício diário, na décima semana, para habituação ao pesquisador e ao ambiente experimental. Utilizaram-se duplos bloqueios farmacológicos (propranolol/atropina e atropina/propranolol) para determinação da FCI, bem como bloqueios farmacológicos autonômicos unilaterais que permitiram a medida do EV, do TV, do ES e do TS. Definições: EV = FC após atropina - FC controle, ES = FC controle - FC após propranolol, TV = FCI - FC após propranolol, TS = FC após atropina - FCI. Registros: batimento-a-batimento, 500Hz (AT/CODAS). Para comparação realizou-se análise de variância de dois caminhos para medidas repetidas, com contraste. Significância estatística, P<0,05. FC e FCI foram menores em T que S, em repouso e nos quatro estágios estudados: FC = 296+6, T vs. 325+16, S; 374+33, T vs. 420+29, S; 380+ 39, T vs. 423+29, S; 407+46, T vs. 434+25, S; 441+48, T vs. 455+30, S; e FCI = 288+28, T vs. 312+18, S; 302+27, T vs. 332+24, S; 301+30, T vs. 339+26, S; 308+30, T vs. 344+30, S; 316+31, T vs. 348+31, S. Não houve diferença na atividade vagal entre T e S, tanto considerando o EV, como o TV, em nenhuma das condições estudadas. A influência simpática para o coração se mostrou semelhante entre T e S, tanto se considerando o ES quanto o TS, em todas as condições estudadas. T e S responderam de forma semelhante aos agonistas muscarínico e adrenérgico. Tanto a FC, quanto a FCI aumentaram do repouso para o exercício, e com o aumento da intensidade do mesmo. A atividade vagal diminuiu do repouso para o exercício, mas apenas em intensidade elevada. A atividade simpática aumentou na passagem do repouso para o exercício, e com o aumento da intensidade do mesmo. Concluiu-se que, em ratos idosos: a) o treinamento físico de moderada intensidade promoveu bradicardia de repouso e atenuação da taquicardia induzida pelo exercício essencialmente à custa de redução da FCI; e b) independentemente da condição de treinamento físico, a estimulação simpática contribuiu para o aumento da FC, em resposta ao exercício, de leve à alta intensidade, enquanto a retirada vagal o fez, apenas em alta intensidade.
We studied the effect of exercise training on heart rate (HR), on intrinsic heart rate (IHR), on vagal effect (VE), on vagal tone (VT), on sympathetic effect (SE) and on sympathetic tone (ST) during both treadmill resting and exercise of progressive intensity (four 5-min stages at 5, 7.5, 10 and 15 m.min-1) in old rats. HR responses to crescent doses of ?-adrenergic (isoproterenol) and muscarinic (metacholine) agonists were also verified. We used 20 male Wistar rats randomly assigned to two groups: trained (T, 28+2 months, 460+36 g) and sedentary control (S, 28+2 months, 461+43 g) rats. T was submitted to a ten-week moderate intensity exercise training program, while S was just handled, three to five times a week, for nine weeks and submitted to five-min bouts of daily exercise during the tenth week for taming and to become accustomed to experimental environment. Double pharmacological blockades (propranolol/ methylatropine and methylatropine/propranolol) were performed in order to determine IHR. Autonomic influences on heart rate were evaluated using also unilateral autonomic pharmacological blockade, which allowed us to measure VE and VT as well as SE and ST. Definitions: VE = HR after atropine - control HR, SE = control HR - HR after propranolol, VT = IHR - HR after propranolol, ST = HR after atropine - IHR. HR was recorded on a beat-to-beat basis with a 500 Hz acquisition frequency (AT/CODAS). For statistical analysis we used two-way ANOVA for repeated measurements with contrast, considering a P<0.05 as statistically significant. T rats had lower HR as well as IHR than their sedentary counterparts both at rest and during all progressive exercise stages: HR = 296+6,T vs. 325+16,S; 374+33,T vs. 420+29,S; 380+39,T vs. 423+29,S; 407+46,T vs. 434+25,S; 441+48,T vs. 455+30,S, respectively; and IHR = 288+28,T vs. 312+18,S; 302+27,T vs. 332+24,S; 301+30,T vs. 339+26,S; 308+30,T vs. 344+30,S; 316+31,T vs. 348+31,S, respectively. Vagal activity was not significantly different between groups, either considering VE or VT. Sympathetic influence was also similar between S and T considering both SE and ST in all of the studied conditions. T and S responded similarly to both muscarinic and ?-adrenergic agonists. Both HR and IHR increased from rest to exercise and with increasing exercise intensity. Vagal activity decreased from rest to exercise but only in high intensity exercise. Sympathetic activity increased from rest to exercise and also with increasing exercise intensity. We concluded that in old rats: a) exercise training of moderate intensity led to resting bradycardia and attenuation of exercise tachycardia essentially due to the decrease in IHR; and b) independently from exercise training status, sympathetic stimulation contributed to HR increase from light to high intensity exercise while vagal withdrawal became important only at high intensity exercise

O gânglio estrelado (GE) é o principal componente da inervação cardíaca extrínseca e está envolvido na gênese de diversas cardiomiopatias. Durante o envelhecimento, o controle neural do coração dos mamíferos é alterado de forma complexa e não clara, geralmente ocasionando decremento da função cardíaca e maior propensão a doenças degenerativas. A ocorrência de resultados dissonantes quanto aos parâmetros morfoquantitativos durante o envelhecimento, como o aumento ou diminuição do número total de neurônios simpáticos, é assunto para discussões interessantes. Esta pesquisa foi conduzida em preás machos (Galea spixii), um pequeno roedor da fauna brasileira. Desta forma, estudou-se o efeito do desenvolvimento pós-natal (maturação e envelhecimento) na macro e microestrutura do gânglio estrelado esquerdo (GEe) de preás, por meio de microscopia quantitativa tridimensional (Estereologia) associada a técnicas de imuno-histoquímica. De acordo com a fase específica do desenvolvimento pós-natal, os animais foram alocados nos seguintes grupos etários: Neonatos, Jovens, Adultos e Senis. Inicialmente, os animais foram submetidos à eutanásia e seus gânglios estrelados esquerdos coletados e fixados em solução de formaldeído (4%) em PBS. Foi realizada amostragem sistemática e uniformemente aleatória (SURS), estimando-se: volume do GEe, volume neuronal e número total de neurônios do GEe. Os principais achados deste estudo foram: i) aumento do comprimento do gânglio - 42% entre Neonato e Senil; 34% entre Jovem e Senil e 35% entre Adulto e Senil; ii) hipertrofia do GEe - 171% entre os grupos Neonato e Adulto; iii) aumento do tecido não neuronal - 268% entre os grupos Neonato e Adulto; iv) estabilidade no número total de neurônios uninucleados, binucleados e total (uni+bi); v) estabilidade no tamanho (volume) dos neurônios uninucleados e binucleados; e vi) estabilidade no número total de neurônios imunorreativos ao Ki-67 (uni+bi). Espera-se que os resultados gerados por esta pesquisa possam esclarecer alguns aspectos estruturais da plasticidade neural durante o desenvolvimento pós-natal de preás, avançando assim o conhecimento acerca da inervação cardíaca extrínseca
The stellate ganglion (SG) is a main component of extrinsic cardiac innervation and is involved in the genesis of various cardiomyopathies. During ageing, the neural control of heart in mammals is altered in the complex shape and unclear, generally cause decrement in the cardiac function and a greater propensity to degenerative diseases. The occurrence of discordant results regarding the morphoquantitative parameters during ageing, such as increase or decrease in the total number of sympathetic neurons, is a subject for interesting discussions. This research was conducted in males preas (Galea spixii), a small rodent of the Brazilian fauna. Therefore, this work aimed to study the effect of postnatal development (maturation and ageing) in the macro and microstructure of the left stellate ganglion (LSG) in preas by dimensional quantitative microscopy (Stereology) associated to immunohistochemistry techniques. According to a specific stage of postnatal development, the animals were allocated into the following age groups: Newborn, Young, Adult and Elderly. The animals were euthanised and the left stellate ganglia were collected and fixed in 4% formaldehyde solution in PBS. A systematic uniformly random sampling (SURS) was performed to estimate: the volume of LSG, neuron volume and the total number of LSG neurons. The main findings of this study were: i) increase in length ganglia - 42% between Newborn and Elderly; 34% between Young and Elderly and 35% between Adult and Elderly; ii) hypertrophy of LSG - 171% between the groups Newborn and Adult; iii) increase of non-neuronal tissue - 268% between the groups Newborn and Adult; iv) stability for the total number of uninucleate neurons, binucleate neurons and total (uni+bi); v) stability in the size (volume) of uninucleate and binucleate neurons; and, vi) stability for the total number of neurons immunorreactive to Ki-67 (uni+bi). It is expected that the results generated for this research may clarify structural aspects of neural plasticity during the postnatal development of preas, thus advancing the knowledge about the extrinsic cardiac innervation

Introduzione. Col progredire dell’età, la capacità dell’organismo di modificare struttura e funzione di organi e apparati in risposta agli stimoli si modifica. Scopo di questo progetto è indagare l’effetto dell’età sul rimodellamento cardiovascolare in risposta all’allenamento aerobico e valutare gli effetti della corsa sulla patologia del ginocchio. Metodi. 237 volontari sani, sedentari, sono stati valutati al basale e dopo 6 mesi di allenamento non supervisionato e il completamento della loro prima maratona, con: 1) risonanza magnetica cardiaca a 1.5T; 2) misurazione non invasiva della pressione arteriosa (PA) centrale e brachiale; 3) risonanza magnetica (MRI) bilaterale del ginocchio a 3.0T. La “età aortica biologica” è stata calcolata al basale dalla relazione tra l’età anagrafica e la rigidità arteriosa. Modificazioni nella rigidità arteriosa sono state valutate a livello dell’aorta ascendente (Ao-A), discendente (Ao-D), della biforcazione polmonare (Ao-P) e del passaggio diaframmatico (Ao-D).Per l’analisi, i soggetti sono stati divisi in due gruppi in base all’età (≥35 anni: O35; 34 anni: U35). Risultati. Le percentuali di infortunio e completamento della corsa sono state simili nei due gruppi. 138 corridori (U35: n =71, femmine =49%; O35: n =67, femmine =51%) hanno completato la corsa. In media, gli U35 sono stati 37 minuti più veloci (12%). L’allenamento si è associato a un piccolo incremento nella massa del ventricolo sinistro (LV) in entrambi i gruppi (3g/m2, p <0.001), ma negli U35 si è osservato anche un aumento del volume biventricolare (volume telediastolico LV [EDV]i +3%; volume telesistolico LV [ESV]i +8%; EDVi del ventricolo destro [RV] +4%, RVESVi +5%; p<0.01 per tutti). La compliance sistemica aortica si è ridotta nell’intero campione del 7% (p=0.020) e, in particolare negli O35, anche le resistenze vascolari sistemiche (-4% nell’intero campione, p=0.04) e la PA (sistolica/diastolica, intero campione: brachiale -4/-3 mmHg, centrale -4/-2 mmHg, tutti p <0.001; O35: brachiale -6/-3 mmHg, centrale -6/-4 mmHg, tutti p<0.001). Al basale, una decade di età anagrafica corrispondeva a una riduzione della distensibilità Ao-A, Ao-P, e Ao-D di 2.3, 1.9, and 3.1 x 10-3 mm Hg-1 rispettivamente (p < 0.05 per tutti). La distensibilità di Ao-D è aumentata (Ao-P: 9%; p = 0.009; Ao-D: 16%; p = 0.002), mentre quella di Ao-A è rimasta invariata. Queste variazioni corrispondono a una riduzione nella “età aortica” di 3.9 anni (95% CI: da 1.1 a 7.6 anni) e 4.0 anni (95% CI: da 1.7 a 8.0 years) (Ao-P e Ao-D, rispettivamente). Il beneficio è stato maggiore in partecipanti di sesso maschile, più anziani e più lenti (p < 0.05 per tutti). La MRI basale ha mostrato segni di danno asintomatico in numerose strutture del ginocchio nella maggioranza degli 82 soggetti esaminati. Dopo la maratona, la MRI ha mostrato una riduzione del punteggio di danno nell’edema midollare subcondrale nei condili tibiali (p=0.011) e femorali (p=0.082). Conclusioni. In soggetti sani e sedentari, un allenamento fisico non supervisionato, di intensità lieve e di media durata induce variazioni misurabili nella struttura e funzione cardiovascolare. L’entità di queste variazioni è dipendente dall’età, con maggior rimodellamento cardiaco osservato nei più giovani e maggior rimodellamento vascolare osservato nei più anziani, fino a una riduzione della PA centrale e rigidità arteriosa equivalenti a una riduzione di ~ 4 anni nell’età vascolare. Inoltre, l’allenamento e corsa di una maratona non sono lesivi sull’articolazione del ginocchio.
Background. Healthy ageing is associated with changes in human’s body ability to modify organs and systems structure and function in response to stimuli. With this project we sought to understand whether remodelling in response to a stimulus, exercise training, altered with healthy ageing and to deepen the knowledge about running effects on the knee joint. Methods. 237 untrained healthy male and female subjects volunteering for their first-time marathon were recruited. At baseline and after 6 months of unsupervised training, race completers underwent tests including 1.5T cardiac magnetic resonance, brachial and non-invasive central blood pressure (BP) assessment and a 3.0T bilateral knee magnetic resonance. Biological “aortic age” was calculated from the baseline chronological age-stiffness relationship. Change in stiffness was assessed at the ascending (Ao-A) and descending aorta at the pulmonary artery bifurcation (Ao-P) and diaphragm (Ao-D). For analysis, runners were divided by age (O35: ≥35y.o.; U35:  34y.o.) Results. Injury and completion rates were similar among groups. 138 runners (under 35 [U35]: n=71, females=49%; over 35 [O35]: n=67, females=51%) completed the race. On average, U35 were faster by 37 minutes (12%). Training induced a small increase in left ventricle (LV) mass in both groups (3g/m2, p<0.001), but U35 also increased ventricular cavity sizes (LV end-diastolic volume [EDV]i +3%; LV end-systolic volume [ESV]i +8%; right ventricle [RV] EDVi +4%, RVESVi +5%; p<0.01 for all). Systemic aortic compliance fell in the whole sample by 7% (p=0.020) and, especially in O35, also systemic vascular resistance (-4% in the whole sample, p=0.04) and blood pressure (systolic/diastolic, whole sample: brachial -4/-3 mmHg, central -4/-2 mmHg, all p <0.001; O35: brachial -6/-3 mmHg, central -6/-4 mmHg, all p<0.001). At baseline, a decade of chronological ageing correlated with a decrease in Ao-A, Ao-P, and Ao-D distensibility by 2.3, 1.9, and 3.1 x 10-3 mm Hg-1, respectively (p < 0.05 for all). Descending aortic distensibility increased (Ao-P: 9%; p = 0.009; Ao-D: 16%; p = 0.002), while remaining unchanged in the Ao-A. These translated to a reduction in “aortic age” by 3.9 years (95% CI: 1.1 to 7.6 years) and 4.0 years (95% CI: 1.7 to 8.0 years) (Ao-P and Ao-D, respectively). The benefit was greater in older, male participants with slower running times (p < 0.05 for all). Pre marathon and pretraining MRI showed signs of damage, without symptoms, to several knee structures in the majority of the 82 middle-aged volunteers. However, after the marathon, MRI showed a reduction in the radiological score of damage in subchondral bone marrow oedema in the condyles of the tibia (p=0.011) and femur (p=0.082). Conclusion. Medium-term, unsupervised, mild intensity physical training in healthy sedentary individuals induces measurable remodelling of both heart and vasculature. This amount is age-dependent, with predominant cardiac remodelling when younger and predominant vascular when older, with a reduction in central blood pressure and aortic stiffness equivalent to a ~ 4-year reduction in vascular age. Training for and running a marathon is associated with improvement in the condition of bone marrow and articular cartilage.

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Universidade Federal de Sao Carlos
The effects of female sex hormones on the cardiovascular system have been the topic of much discussion and controversy in the literature. Nevertheless, many scientists believe that estrogens play an important cardioprotective role in premenopausal women, with their effects being observed directly on blood vessels or indirectly by the promotion of an antiatherogenic lipid profile. In recent years, studies have reported that estrogen hormone levels may also influence autonomic control of heart rate (HR) and exercise tolerance. However, other researches have found no modification of these parameters in function of hormone therapy. Within this context, three studies were conducted to verify whether estrogen therapy (ET) could attenuate the age-related decline in autonomic control of HR under resting and exercise conditions and aerobic capacity of healthy women. Thirteen young women (mean age: 24 years), 10 postmenopausal women undergoing ET (PMET, mean age: 53 years) and 15 postmenopausal women not undergoing ET (PMnET, mean age: 56 years) were studied. Hormonal treatment consisted of 0.625 mg/day of conjugated equine estrogens. In the first study, the effect of age and ET on HR variability (HRV) under resting conditions in the supine and sitting positions was evaluated. HRV was analyzed by time (TD) and frequency domain (FD) methods. In this study, higher values of the temporal indices of HRV were observed for the young group. In the analysis of FD, the PMnET group presented lower values in the indices reflecting vagal activity and higher values in the indices reflecting sympathetic activity compared to the young group (supine position) and to the PMET group (sitting position). These results suggest that HRV decreases during aging and that ET may attenuate this process by promoting a reduction of sympathetic activity on the heart and contributing to the cardioprotective effect of estrogen hormones. In the second study, the effect of age and ET on the autonomic control of HR during dynamic exercise and anaerobic threshold (AT) was evaluated. Dynamic exercise was performed on a cycle ergometer starting at 15 W and followed by 5 W increments, until the loss of HR response stabilization was identified by a semiparametric model, characterizing AT. The autonomic control of HR during exercise was analyzed by vagal withdrawal at the beginning of exercise and by calculating the rMSSD index of the stable interval of each workload level. The vagal withdrawal and the rMSSD index were higher for the young group at the workloads studied. The young group also presented higher workload and HR values at AT compared to the postmenopausal groups. These results suggest that autonomic modulation of HR during exercise and aerobic capacity are strongly influenced by age. Hypoestrogenism and ET had no effect on the variables studied. In the third study, the effect of age and ET on cardiorespiratory responses during a cardiopulmonary exercise test was evaluated. This test was performed on a cycle ergometer with 10 to 20 W/min increments until physical exhaustion. The AT was determined by graphic visual analysis of the curves for carbon dioxide output and oxygen uptake ( O2). Higher workload and HR values both at AT and at the peak of exercise were observed for the young group. HR was similar between groups at AT and significantly higher at peak exercise for the young group. The percentages of AT in relation to peak exercise for O2 and HR values were higher for the postmenopausal groups. These results suggest that ET had no effect on cardiorespiratory responses during the incremental exercise test. In conclusion, the results obtained in the three studies suggest that the vagal-protective effect of estrogen hormones detected at rest is not maintained during exercise. In addition, exercise tolerance does not seem to depend on the physiological levels of estrogens. On this basis, the present findings support the importance of the prescription of physical exercise in the clinical orientation for climacteric women
Os efeitos dos hormônios sexuais femininos sobre o sistema cardiovascular tem sido um tópico de muita discussão e controvérsias na literatura. Apesar disso, muitos cientistas acreditam que os estrogênios exercem importante papel cardioprotetor nas mulheres pré-menopausadas, sendo seus efeitos observados diretamente sobre os vasos sangüíneos ou indiretamente através da promoção de um perfil lipídico antiaterogênico. Nos últimos anos, tem sido reportado que o controle autonômico da freqüência cardíaca (FC) e a tolerância ao exercício também podem ser influenciados pelos níveis hormonais de estrogênios. No entanto, outros pesquisadores não encontraram qualquer modificação nesses parâmetros em função da terapia hormonal. Dentro desse contexto, foram realizados três estudos, com o objetivo de verificar se a terapia estrogênica (TE) poderia atenuar o declínio relacionado à idade no controle autonômico da FC, em condições de repouso e exercício, e na capacidade aeróbia de mulheres saudáveis. Para isso foram estudadas 13 mulheres jovens (média etária de 24 anos), 10 na fase pós-menopausa em uso de TE (PMCTE: média etária de 53 anos) e 15 na pós-menopausa sem uso de TE (PMSTE: média etária de 56 anos). A TE consistiu de 0,625 mg/dia de estrogênios eqüinos conjugados. No primeiro estudo, foi avaliado o efeito da idade e da TE sobre a variabilidade da FC (VFC) durante o repouso, nas posições supina e sentada. A VFC foi analisada no domínio do tempo (DT) e da freqüência (DF). Nesse estudo foram observados maiores valores dos índices temporais de VFC para o grupo jovem. Na análise no DF, o grupo PMSTE apresentou menores valores dos índices que refletem a atividade vagal e maiores valores dos índices que refletem a atividade simpática em relação aos grupos jovem (posição supina) e PMCTE (posição sentada). Esses resultados sugerem que a VFC diminui com o envelhecimento e que a TE pode atenuar esse processo, promovendo uma redução na atividade simpática sobre o coração, e contribuindo para o efeito cardioprotetor dos hormônios estrogênios. No segundo estudo, foi avaliado o efeito da idade e da TE sobre o controle autonômico da FC durante exercício dinâmico e o limiar de anaerobiose (LA). O exercício dinâmico foi realizado em cicloergômetro, sendo iniciado na potência de 15 W e seguido por incrementos de 5 W, até que fosse identificada a perda da estabilização da resposta da FC pelo modelo semiparamétrico, caracterizando o LA. O controle autonômico da FC durante o exercício foi analisado por meio da retirada vagal no início do exercício e pelo cálculo do índice rMSSD do trecho estável de cada nível de potência. A retirada vagal e o índice rMSSD foram maiores para o grupo jovem, nas potências estudadas. As jovens também apresentaram maiores valores de potência e de FC no LA em relação aos grupos na pós-menopausa. Esses resultados sugerem que a modulação autonômica cardíaca durante o exercício e a capacidade aeróbia são fortemente influenciados pela idade. Ambos, hipoestrogenismo e TE, não exerceram qualquer influência sobre as variáveis estudadas. No terceiro estudo, foi avaliado o efeito da idade e da TE sobre as respostas cardiorrespiratórias durante teste de exercício cardiopulmonar. Esse teste foi realizado em cicloergômetro, com incrementos de 10 a 20 W/min até a exaustão física. O LA foi determinado visualmente pela análise das curvas de produção de dióxido de carbono e de consumo de oxigênio ( O2). Foram observados maiores valores de potência e de FC tanto no LA como no pico do exercício para o grupo jovem. A FC foi similar entre os grupos no LA e, significantemente maior no grupo jovem, no pico do exercício. Os valores percentuais do LA em relação ao pico do exercício para os dados de O2 e de FC foram maiores para os grupos na pós-menopausa. Esses resultados sugerem que a TE não teve influencia sobre as respostas cardiorrespiratórias durante teste de exercício incremental. Finalizando, os resultados obtidos nos três estudos sugerem que o efeito protetor vagal dos hormônios estrogênios evidenciado durante o repouso não se mantém durante o exercício. Além disso, a tolerância ao exercício parece não depender dos níveis fisiológicos dos estrogênios. Desse modo, nossos achados reforçam a importância da prescrição de exercícios físicos na orientação clínica das mulheres no climatério

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The aim of the present study was to analyse heart rate recovery (HRR) and chronotropic index (CI) after treadmill Bruce test in obese elderly women classified on the basis of relative manual grip strength. Methods: Eighty-eight obese elderly women who were between the ages of 60 and 87 participated in the study and were categorized and enrolled to one of two groups based on lower (< 1.51 m²) or higher (≥ 1.51 m²) relative handgrip strength, respectively. The heart rate recovery in the first and second minutes following the treadmill exercise test and the chronotropic index were compared between groups. Results: The higher relative handgrip strength group presented a significantly higher peak heart rate (p= 0,019) during exercise and a faster HRR at the first (p = 0.003) and second minutes (p = 0.002) after the ergometric test compared to the low manual grip strength group (p=0,001). Furthermore, there was a tendency (p = 0.059) towards a significantly higher CI, six-minute walk test (p = 0.001) and low time up and go time in the group of high relative manual grip strength compared to the low force group. Conclusion: In conclusion, elderly women with greater relative handgrip strength also demonstrated a better heart rate response during and following exercise and tendency to higher chronotropic index, possibly indicating better autonomic balance.
O objetivo do presente estudo foi analisar a recuperação da frequência cardíaca (RFC) e o índice cronotrópico (IC) após teste de Bruce em esteira em mulheres idosas obesas classificadas com base na força de preensão manual relativa (FPMR). Métodos: Participaram voluntariamente do estudo 88 mulheres idosas obesas entre 60 e 87 anos que foram categorizadas em dois grupos: baixa força de preensão manual relativa (<1,51 m²) e alta força de preensão manual relativa (≥ 1,51 m²). A RFC no primeiro e no segundo minutos e o índice cronotrópico após o teste ergométrico em esteira foram comparados entre os grupos. Resultados: O grupo de alta força de preensão manual relativa apresentou valores de frequência cardíaca máxima significativamente maiores durante o teste ergométrico (p= 0,019), RFC mais rápida no primeiro (p = 0,003) e segundo minutos (p = 0,002) após o teste ergométrico comparado ao grupo de baixa força de preensão manual relativa (p=0,001). Observamos tendência (p = 0,059) em direção a um IC significativamente maior, Teste de caminhada de 6 minutos (p = 0,001) e baixo tempo no time up and go no grupo de alta força de preensão manual relativa comparado ao grupo de baixa força. Conclusão: Mulheres idosas com alta força de preensão manual relativa apresentam uma melhor resposta da frequência cardíaca durante e após o teste ergométrico, tendência a um índice cronotrópico superior possivelmente indicando um melhor equilíbrio autonômico após o esforço físico e maior capacidade funcional.

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Universidade Federal de Minas Gerais
The purpose of the present study was to evaluate the effects of the aging and the regular physical activity on the autonomic control of heart rate (HR) at rest and during deep breath test (DBT) in healthy men. Nine young sedentary (mean = 22.67 ±2.45 years), sixteen young active (mean = 22.38 ±2.13 years), eight sedentary older (mean = 63.5 ±2.39 years) and eight older active (mean = 61 ±1.6 years) men were studied. Electrocardiogram was continuously recorded during 15 minutes (rest), 4 minutes (DBT, with breath rate at 5 to 6 cycles/minute) and 1 minute (recovery) in supine position. The HR (bpm) and the R-R intervals (RRi) (ms) were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF), and as the LF/HF. The HR and the RRi were analyzed by the respiratory sinus arrhythmia (RSA) indices: expiration/inspiration ratio (E/I) and inspiration-expiration difference (∆IE). The HR was lower in the activity groups than to the matched-age sedentary groups. The older sedentary group had lower heart rate variability (HRV), E/I and ∆IE than young ones. The older active group showed higher RMSSD and HF component than matched-age sedentary group (45.04 and 28.78 ms, 58,167 and 12,218 ms2/Hz, P<0.05; respectively). No differences were found between young and older active groups for RMSSD (61.71 and 45.04 ms, respectively) and HRV (TP:130,816 and 125,710, LFa:33,295 and 32,611, HFa:84,346 and 58,167, ms2/Hz, respectively) and DBT indices (E/I: 1.40 and 1.35, ∆IE: 23 and 18, respectively). The results show that aging associates with inactivity reduces the HRV. However, the regular physical activity increases the HRV, independent of age, suggesting attenuation the effects of the aging in the autonomic control of the heart rate.
O presente estudo teve como objetivo avaliar os efeitos da idade e da atividade física regular sobre o controle autonômico da freqüência cardíaca (FC) durante o repouso e durante a manobra para acentuar a arritmia sinusal respiratória (MASR) em homens saudáveis. Participaram do presente estudo, 9 jovens sedentários (média= 22,67 ±2,45 anos), 16 jovens ativos (média= 22,38 ±2,13 anos), 8 idosos sedentários (média= 63,5 ±2,39 anos) e 8 idosos ativos (média= 61 ±1,6 anos). O traçado eletrocardiográfico foi registrado durante 15 minutos (repouso com respiração espontânea), 4 minutos (MASR, com freqüência respiratória mantida entre 5 a 6 ciclos/minuto) e 1 minuto de recuperação. A freqüência cardíaca (FC), em bpm, e os intervalos RR (iR-R), em ms, foram analisados pelo domínio do tempo (índice RMSSD) e pelo domínio da freqüência. Os componentes da potência espectral foram expressos em valores absolutos (a) e em unidades normalizadas (un) para a densidade total de potência (DTP), as bandas de baixa freqüência (BF), alta freqüência (AF) e razão BF/AF. A FC obtida durante a manobra MASR foi analisada a partir dos índices: razão expiração/inspiração dos iR-R (E/I) e de sua variação durante a inspiração-expiração (∆IE). Os grupos ativos apresentaram valores inferiores de FC de repouso em comparação aos controles sedentários de mesma idade. O grupo idoso sedentário apresentou menor variabilidade da variabilidade da freqüência cardíaca (VFC), E/I e ∆IE que o grupo jovem sedentário. O grupo idoso ativo mostrou valores superiores de RMSSD e da banda de HF em relação ao grupo sedentário idoso (45,04 e 28,78 ms, 58.167 e 12.218 ms2/Hz, p<0,05; respectivamente). Diferenças estatísticas não foram encontradas entre o grupo jovem ativo e idoso ativo para o RMSSD (61,71 e 45,04 ms, respectivamente) e para a VFC (DTP: 130.816 e 125.710, LFa: 33.295 e 32.611, HFa: 84.346 e 58.167, ms2/Hz, respectivamente) e para os índices da ASR (E/I: 1,40 e 1,35, ∆IE: 23 e 18, respectivamente). Para os grupos sedentários foi observado correlação negativa entre os índices DTP, AFa, E/I e ∆IE e a idade (p<0,05), sendo que o mesmo não pode ser observado nos grupos ativos. Os resultados sugerem que o envelhecimento associado ao sedentarismo provoca reduções na VFC, representadas pela diminuição da atividade vagal sobre o coração, determinada tanto pela análise no domínio da freqüência como pelos índices da arritmia sinusal respiratória. Entretanto, a atividade física regular aumenta a VFC, independentemente da idade, e atenua as alterações, decorrentes do processo de envelhecimento, no controle autonômico da freqüência cardíaca.

O treinamento físico resistido tem sido enfaticamente incentivado, proporcionando efeitos favoráveis na força e endurance muscular, na função cardiovascular, metabolismo e na redução do risco cardiovascular. No entanto, é escassa a literatura sobre os ajustes cardiovasculares, ventilatórios e metabólicos no exercício resistido na população idosa. Além disso, pouco é sabido sobre tais ajustes na carga crítica (CC), a qual demarcaria a transição do exercício moderado para o exercício intenso nesta modalidade de exercício. Dessa forma, os objetivos deste trabalho são: avaliar o comportamento das respostas cardiovasculares, respiratórias e metabólicas durante o exercício físico resistido (Leg Press 45º) em diferentes intensidades, bem como determinar a intensidade da CC e ainda nessa intensidade comparar as respostas da freqüência cardíaca (FC), pressão arterial sistólica (PAS), ventilação (VE), consumo de oxigênio (\'VO IND.2\'), produção de dióxido de carbono (\'VCO IND.2\'), quociente respiratório (QR), percepção subjetiva de esforço (PSE) e lactato sangüíneo ([Lac]) obtidas durante exercício entre dois grupos (jovens e idosos). Participaram deste estudo 28 indivíduos do sexo masculino, sendo 15 jovens e 13 idosos, aparentemente saudáveis, sendo que a média de idade dos jovens foi de 22,7 ± 2,5 anos, massa média de 77,6 ± 10,2 kg e estatura média de 180,0 ± 10,0 cm e nos idosos a média de idade foi de 68,6 ± 4,0 anos, massa média de 76,7 ± 7,5 kg e estatura média de 170,0 ± 1,0 cm, não etilistas, não tabagistas, e sem distúrbios cardiorrespiratórios, neurológicos, metabólicos e articulares. Durante todos os procedimentos foram monitoradas PA, FC e eletrocardiograma nas derivações MC5, DII e V2 modificadas, sendo que foram realizados: teste de 1RM em exercício resistido no Leg Press 45º; teste de esforço físico dinâmico resistido com diferentes percentuais de 1RM, testados de acordo para obtenção da carga crítica, pela regressão linear dos pontos apurados na construção do gráfico: carga X inverso do tempo (tempo = duração do exercício até a fadiga). Com relação ao tempo de execução e o número de repetições não houve diferenças entre os grupos (p = 0,25 e p = 0,49; respectivamente); para a FC e PAS, temos para o grupo jovem uma resposta exacerbada da FC comparada aos idosos durante exercício (p<0,0001), sendo que o comportamento da PAS revela-se de modo contrário, havendo assim uma resposta mais acentuado para o grupo idoso (p<0,0197). A [Lac] foi maior em jovens na intensidade da CC (p = 0,0014), bem como o valor de PSE (0,00021). Para os parâmetros ventilatórios (VE, \'VO IND.2\' e \'VCO IND.2\') temos maiores valores para o grupo jovem também na fase de exercício para diferentes intensidades, principalmente na CC (p<0,0001, para as três variáveis). Além disso, foi possível determinar a carga crítica para ambos os grupos, sendo que essa foi em torno de 38% 1RM (p = 0,22). Dessa forma, esse foi o primeiro estudo que avaliou e comparou as respostas fisiológicas entre jovens e idosos em diferentes intensidades da RM, no exercício de Leg Press 45º, assim como na CC.
The resistance training has been strongly encouraged, providing favorable effects on muscular strength and endurance, cardiovascular function, metabolism and cardiovascular risk reduction. However, there is little literature about the cardiovascular, ventilation and metabolic responses in resistance exercise in the elderly. Moreover, little is known about such adjustments in the critical load (CL), which indicates the transition of moderate to intense exercise in this type of exercise. Thus, the objectives of this study are: To evaluate the cardiovascular, respiratory and metabolic changes during resistance exercise (leg press 45º) at different intensities and to determine the intensity of the CL and even that intensity to compare the responses of heart rate (HR), systolic blood pressure (SBP), ventilation (VE), oxygen consumption (\'VO IND.2\'), production of carbon dioxide (\'VCO IND.2\'), respiratory quotient (RQ), perceived exertion (PSE) and blood lactate ([Lac]) obtained during exercise between two groups (young and old). Participated in this study 28 males, 15 young and 13 elderly, apparently healthy, with an average age of the young was 22.7 ± 2.5 years, mean weight 77.6 ± 10.2 kg and mean height of 180.0 ± 10.0 cm, and in the elderly the average age was 68.6 ± 4.0 years, mean weight 76.7 ± 7.5 kg and mean height of 170.0 ± 1.0 cm, non-alcoholic non-smoker, and without cardio-respiratory, neurological, metabolic and joints disorders. During all procedures were monitored BP, HR and ECG at MC5, DII and V2 modified, and were carried out: 1RM resistance exercise on the leg press at 45º; exercise stress test dynamic resistance with different percentages of 1RM tested agreement for obtaining the critical load, the linear regression of the points made during the construction of the graph: load X reverse of time (time = duration of exercise until fatigue). Regarding the execution time and number of repetitions no differences between the groups (p = 0.25 and p = 0.49, respectively) for the HR and SBP, we have exacerbated response of HR for a young group compared to elderly, during exercise (p < 0.0001), and the SBP appears to be so contrary, so there is more pronounced for the elderly group (p < 0.0197). The [Lac] was greater in young people in the CC intensity (p = 0.0014), as well as the value of PSE (0.00021). For the ventilatory parameters (VE, \'VO IND.2\' and \'VCO IND.2\') have higher values in the young group also during the exercise for different intensities, mainly in the CC (p < 0.0001 for the three variables). Furthermore, it was possible to determine the CL for both groups, and this was around 38% 1RM (p = 0.22). Thus, this was the first study that evaluated and compared the physiological responses between young and old in different intensities of 1RM in the exercise of Leg Press 45º, as in CL.

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Universidade Federal de Minas Gerais
The aging process affects many systems of the human body, including: autonomic nervous system, which can be assessed by heart rate variability (HRV); cellular structures, such as telomere length; and mechanisms of regulation of the inflammatory process, which can be evaluated by inflammatory markers such as high-sensitivity C-reactive protein (hsCRP). The combined analysis of these variables enables the study of the aging process in a multidimensional way. Additionally, the effects of hormone replacement therapy (HRT) on HRV are contradictory. In this way, we conducted the study I, which aimed to investigate the effects of HRT on HRV in healthy postmenopausal women. Two groups were evaluated: Group 1 (G1): 20 women who did not use HRT (60 ± 5.89 years) and group 2 (G2): 20 women undergoing HRT (59 ± 5.70 years). The electrocardiogram was recorded in supine position for 10 min. Spectral analysis included low and high frequency in absolute (LF and HF) and normalized (LFnu and HFnu) units. LF/HF ratio was also calculated. Symbolic analysis (0V%, 1V%, 2LV% e 2UV%), Shannon and conditional entropy were calculated. LF, LFnu and LF/HF ratio were higher, whereas HFnu was lower in G2 than in G1. Correlations between complexity indices and HFnu were significant and positive only in G1. We conclude that women undergoing HRT had higher cardiac sympathetic modulation and reduced cardiac vagal modulation compared to women not using HRT. Moreover, the expected positive relationship between cardiac vagal modulation and HRV complexity was found only in the group not undergoing HRT, indicating that vagal modulation in women under therapy drop below a minimum value necessary to the association to become apparent, suggesting an unfavorable cardiac autonomic modulation in spite of HRT. Considering the findings of the study I, we chose to adopt the use of the therapy as an exclusion criterion for the study II. Thus, the study II aimed to examine the aging effect on heart rate variability in supine and standing, on serum hsCRP and leukocyte telomere length, as well as to verify the age at which the changes caused by aging process are accentuated. One hundred and ten volunteers were divided into five groups according to age: G21-30 years, G31-40 years, G41-50 years, G51-60 years, and G61-70 years. Venous blood samples were collected for measurements of serum hsCRP and telomere length. ECG signals were recorded in rest supine and standing (15 min in each posture). HRV was assessed by spectral analysis in low and high frequencies in absolute (LF e HF) and normalized (LFnu e HFnu) units; symbolic analysis (0V%, 1V%, 2LV% e 2UV%); Shannon entropy; and complexity index (CI) and normalized CI (NCI) from conditional entropy. The main results were: 1) HF and 2UV% reduction (vagal modulation) in G51-60, and 0V% increase (sympathetic modulation) and NCI reduction (complexity) in G61-70, in supine; 2) less efficient response to postural change from supine to standing with advancing age; 3) hsCRP increase in G51-60; 4) telomere shortening in G61-70; 5) in supine, HRV indices showed stronger relationship with the principal component of most relevance from the multivariate principal component analysis, compared to hsCRP and telomere length. Considering that HRV indices in supine had a stronger association with the aging process, we can conclude that the decrease in cardiac vagal modulation may have influenced the increase in serum hsCRP (although normal values), in G51-60, since this effect is described by the cholinergic anti-inflammatory pathway. Decreased cardiac vagal modulation and increased hsCRP may have contributed to the telomere shortening identified in the following decade (G61-70). In this way, we must consider the importance of preventive actions prior to the onset of aging effects, particularly in the 41-50 age range, in an attempt to attenuate the natural effects of senescence.
O envelhecimento exerce influência sobre vários sistemas do corpo humano, dentre eles: sistema nervoso autonômico, que pode ser avaliado pela variabilidade da frequência cardíaca (VFC); estruturas celulares, como o comprimento de telômeros; e mecanismos reguladores de processos inflamatórios, que podem ser avaliados por marcadores inflamatórios, como a proteína C-reativa ultra sensível (PCRus). A análise conjunta dessas variáveis permitiria o estudo do processo de envelhecimento de forma multidimensional. Adicionalmente, são controversos os efeitos da terapia de reposição hormonal (TRH) sobre a VFC. Assim, foi realizado o estudo I, o qual teve por objetivo investigar os efeitos da TRH na VFC em mulheres pós-menopáusicas saudáveis. Foram avaliados dois grupos: grupo 1 (G1): 20 mulheres que não faziam uso de TRH (60 ± 5,89 anos) e grupo 2 (G2): 20 mulheres submetidas à TRH (59 ± 5,70 anos). O eletrocardiograma foi registrado na posição supina por 10 min. A análise espectral incluiu a baixa e a alta frequência em unidades absolutas (BF e AF) e normalizadas (BFun e AFun). A relação BF/AF também foi calculada. A análise simbólica (0V%, 1V%, 2LV% e 2UV%), e entropias de Shannon e condicional também foram calculadas. BF, BFun e a razão BF/AF foram maiores, enquanto AFun foi menor no G2 do que no G1. As correlações entre índices de complexidade e AFun foram significativos e positivos apenas no G1. Concluímos que mulheres submetidas à TRH apresentaram maior modulação cardíaca simpática e menor modulação cardíaca vagal em comparação às que não faziam a terapia. Além disso, a relação positiva esperada entre modulação cardíaca vagal e a complexidade da VFC foi encontrada apenas no grupo não submetido à TRH, indicando que a modulação vagal em mulheres sob a terapia não atinge um valor mínimo necessário para a associação se tornar aparente, sugerindo uma modulação autonômica cardíaca desfavorável, apesar da TRH. A partir dos achados do estudo I, optou-se por adotar, como critério de exclusão para o estudo II, o uso da terapia. Assim, o estudo II teve por objetivo analisar o efeito do envelhecimento sobre a VFC nas posições supina e ortostática, os níveis séricos da PCRus e o comprimento de telômeros leucocitários, além de verificar em qual faixa etária se acentuam as alterações provocadas pelo processo de envelhecimento. Foram avaliados 110 voluntários, divididos em cinco grupos, de acordo com a idade: G21-30 anos, G31-40 anos, G41-50 anos, G51-60 anos e G61-70 anos. Amostras de sangue venoso foram coletadas para medidas de PCRus e comprimento de telômeros. Os sinais eletrocardiográficos foram registrados em repouso nas posições supina e ortostática (15 min em cada postura). A VFC foi avaliada por índices de baixa e alta frequências em unidades absolutas (BF e AF) e normalizadas (BFun e AFun) da análise espectral; índices 0V%, 1V%, 2LV% e 2UV% da análise simbólica; entropia de Shannon; e índice de complexidade (IC) e IC normalizado (ICN) da entropia condicional. Os principais resultados foram: 1) redução de AF e 2UV% (modulação vagal) em G51-60, além de aumento de 0V% (modulação simpática) e diminuição de ICN (complexidade) em G61-70 na posição supina; 2) resposta menos eficiente à manobra de mudança postural de supino para ortostatismo com o avanço da idade; 3) aumento da PCRus em G51-60; 4) encurtamento do comprimento de telômeros em G61-70; 5) na posição supina, os índices da VFC apresentaram relação mais alta com o componente principal de maior relevância, proveniente da análise multivariada por componentes principais, em comparação à PCRus e ao comprimento de telômeros. Considerando-se que os índices da VFC na posição supina apresentaram uma associação mais forte com o envelhecimento, podemos concluir que a diminuição da modulação cardíaca vagal possa ter contribuído para o aumento dos níveis séricos de PCRus (apesar dos valores estarem dentro de faixa de normalidade), na faixa etária de 51 a 60 anos, uma vez que este efeito é descrito pela via anti-inflamatória colinérgica. A diminuição da modulação cardíaca vagal e o aumento da PCRus podem ter contribuído para o encurtamento de telômeros, identificado na década seguinte, de 61 a 70 anos. Dessa maneira, torna-se importante a proposição de ações preventivas em faixas etárias anteriores ao início das alterações provocadas pelo envelhecimento, especialmente na década de 41 a 50 anos, na tentativa de atenuar os efeitos naturais da senescência.

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Universidade Federal de Sao Carlos
The ageing process is known to affect different tissues and systems. It is well-established that age-associated changes in cardiovascular structure and function are related to the risk of cardiovascular diseases. Because of the vast amount of cardiovascular modifications observed with ageing, the present study focused on three important topics: heart rate variability (HRV), blood pressure variability (BPV) and endothelial dysfunction. Furthermore, we also investigated the effects of physical activity (endurance and strength) on the autonomic control of heart rate (HR), which might be used as non-pharmacological therapy. Thirty five young subject between 18 and 30 years old (14 sedentary men, 5 sedentary women and 16 active men) and thirty eight middleaged/older subjects between 55 and 70 years old (16 sedentary men, 14 sedentary women and 8 active men) were studied. In addition, the subjects are distributed among 3 different studies. In the first one, the effects of the ageing process and active life-style on the autonomic control of HR were investigated in young and middleaged/older subjects. Electrocardiogram was recorded during 15 minutes of rest and 4 minutes of controlled breathing (5 to 6 cycles/min) in the supine position. HR and RR intervals were analyzed by time and frequency domain methods. The active groups presented lower HR and higher HRV (time domain) than the sedentary groups, whereas both middle-aged/older groups showed lower HRV (frequency domain). Additionally, interaction between ageing and life-style effects was observed for respiratory sinus arrhythmia (ASR) indexes (calculated during the controlled breathing test). The sedentary middle-aged/older group presented lower ASR magnitude than the other groups studied. The results suggest that ageing reduces HRV, however, regular physical activity improves vagal modulation on the heart and, consequently, attenuates the effects of ageing on the autonomic control of HR. In the second study, we aimed to investigate if strength training is able to improve cardiac autonomic control in healthy middle-aged/older men. HRV was evaluated before and after 12 weeks of isokinetic eccentric strength training (2days/week, 2-4 sets of 8-12 repetitions at 75-80% peak torque), involving knee flexion and extension. Strength training decreased the systolic blood pressure and increased the torque. However, an autonomic imbalance towards sympathetic modulation predominance was induced by an unknown mechanism. In the third study, we evaluated the effect of ageing on the BPV and endothelial function. We also sought for correlations between increased BPV and impaired endothelium dependent-dilation (EDD) in the middle-aged/older group. Intra-brachial artery BPV and conduit vessel EDD (brachial artery flow-mediated dilation, FMD) were determined in healthy young and middle-aged/older subjects. Moreover, endothelial function of resistance vessels was evaluated by venous occlusion plethysmoghaphy in the middle-aged/older group. The young group presented lower systemic oxidative stress, lower systolic BPV and higher FMD compared with the middle-aged/older group. After split this group according to the BPV, lower FMD was observed in the middleaged/older group with higher BPV. In addition, FMD was inversely correlated to BPV. The lower BPV group showed a great reduction (55%) in the forearm blood flow responses when NG-monometyl-L-arginine (nitric oxide inhibitor) was co-infused with acetylcholine (vs 14% in the higher BPV group). The results suggest that ageing process increases BPV and reduces endothelial function. Additionally, middle-aged/older subjects with higher BPV also have impaired EDD compared with their peers with lower BPV. General Conclusions: the results from the studies described above suggest that ageing process causes decrease of HRV, increase of BPV and decrease of endothelial function. Moreover, aerobic exercise has a cardioprotector effect, since it was able to attenuate the ageing effects on the cardiac vagal modulation. This same benefit, however, was not observed after 12 weeks of eccentric strength training. On the other hand, the strength training program performed by healthy older subjects modified the sympato-vagal balance toward the sympathetic modulation. Finally, systolic BPV oscillations seem to have a narrow relationship with vasodilation mediated by nitric oxide. Then, more studies are needed to clarify the cause-effect relation between those important variables.
O envelhecimento é um processo complexo que causa alterações em vários sistemas do organismo. Em relação ao sistema cardiovascular, modificações na sua estrutura e função estão diretamente relacionadas com o risco aumentado de desenvolvimento de doenças cardiovasculares em idosos. Dentre as diversas alterações cardiovasculares observadas com o envelhecimento, apenas as relacionadas à variabilidade da freqüência cardíaca (VFC), variabilidade da pressão arterial (VPA) e disfunção endotelial foram abordadas no presente estudo. Além disso, foram também investigados os efeitos de dois tipos distintos de exercício físico, ou seja, de resistência aeróbia e de força muscular, sobre o controle autonômico da freqüência cardíaca (FC) de sujeitos saudáveis, como uma forma alternativa de terapia não-farmacológica. Participaram do presente estudo: 35 sujeitos jovens na faixa etária de 18 a 30 anos (14 homens sedentários, 5 mulheres sedentárias e 16 homens ativos) e 38 sujeitos meia-idade/idosos na faixa etária de 55 a 70 anos (16 homens sedentários, 14 mulheres sedentárias e 8 idosos ativos), os quais estão distribuídos em 3 estudos distintos. No primeiro estudo, os efeitos do envelhecimento e do estilo de vida sobre o controle autonômico da FC foram investigados em jovens e meiaidade/idosos com padrão de vida sedentário ou ativo. O sinal eletrocardiográfico foi obtido durante 15 minutos de repouso e 4 minutos de respiração controlada (5-6 ciclos/min), ambos na posição supina. A FC e os intervalos RR foram analisados no domínio do tempo e da freqüência. Adicionalmente, os índices da arritmia sinusal respiratória (ASR) também foram calculados. Os grupos ativos apresentaram menor FC e maior VFC (domínio do tempo) em relação aos grupos sedentários, enquanto que ambos os grupos idosos apresentaram menor VFC (domínio da freqüência). Além disso, foi observado interação entre idade e estilo de vida, já que a magnitude da ASR foi menor no grupo meia-idade/idoso sedentário comparativamente aos demais grupos. Os resultados indicam que a VFC reduz com o aumento da idade. Entretanto, a atividade física regular produz efeitos positivos sobre a modulação vagal cardíaca e, conseqüentemente, atenua os efeitos do envelhecimento sobre o controle autonômico da FC. No segundo estudo, foi avaliado se o treinamento de força excêntrica é capaz de modificar o controle autonômico da FC de idosos saudáveis. A VFC foi avaliada, durante o repouso supino e sentado, após 12 semanas de treinamento de força isocinética excêntrica (extensão e flexão do joelho, 2 dias/semana, 2-4 séries de 8-12 repetições, 75-80% do pico de torque). O treinamento de força foi capaz de aumentar o torque muscular e reduzir a pressão arterial (PA) sistólica de idosos saudáveis. Entretanto, o mesmo causou um desbalanço simpato-vagal, em direção a predominância simpática, o qual foi produzido por mecanismos desconhecidos. No terceiro estudo, foi avaliado se a VPA está aumentada com o avançar da idade e, ainda, se a mesma tem alguma relação com reduções na vasodilatação endotélio-dependente (VED) em sujeitos meiaidade/idosos saudáveis. A VPA intra-arterial e a VED (dilatação mediada por fluxo, DMF) da artéria braquial (i.e., vaso de condutância) foram avaliadas em sujeitos jovens e meia-idade/idosos de ambos os sexos. Adicionalmente, o grupo meia-idade/idoso também foi submetido à pletismografia de oclusão venosa para avaliar a função endotelial dos vasos de resistência. Os jovens apresentaram menor estresse oxidativo sistêmico, menor VPA sistólica e maior DMF, comparativamente ao grupo meia-idade/idoso. Quando esse grupo foi dividido de acordo com a VPA, observou-se DMF reduzida no grupo com alta VPA. Adicionalmente, a DMF mostrou correlação inversa com a VPA. Em relação aos vasos de resistência, o grupo com baixa VPA mostrou redução de 55% na resposta do fluxo sangüíneo quando NG-monometil-L-arginina (inibidor da produção de óxido nítrico) foi co-infudido com acetilcolina (vs 14% no grupo com alta VPA). Os resultados indicam que o envelhecimento causa redução da função endotelial e aumento da VPA. Além disso, sujeitos meia-idade/idosos com alta VPA apresentam DMF reduzida quando comparados aos seus pares com baixa VPA. Conclusão geral: os resultados obtidos nos três estudos sugerem que o envelhecimento causa redução na VFC, aumento da VPA e redução da função endotelial. Além disso, a atividade física aeróbia possui um efeito cardioprotetor, já que essa foi capaz de atenuar os efeitos do envelhecimento sobre a modulação vagal cardíaca. Entretanto, esses efeitos benéficos não foram observados com o treinamento de força excêntrica, pois 12 semanas de treinamento alteraram o balanço simpato-vagal em direção a modulação simpática. Por fim, o aumento nas oscilações da PA sistólica mostrou uma estreita relação com a vasodilatação mediada pelo óxido nítrico, a qual necessita de maiores investigações no sentido de determinar a relação de causa e efeito entre essas duas importantes variáveis.

BACKGROUND: The pathophysiological changes of the aging human heart include left ventricular (LV) hypertrophy, diastolic dysfunction, increased cardiac fibrosis and reduced inotropic reserve. These changes make aged myocardium more susceptible to stress, leading to a high prevalence of cardiovascular diseases in the elderly population. The application of genetically modified aged mice has provided direct evidence of several critical molecular mechanisms involved in cardiac aging, such as altered adrenergic signaling. Importantly, both animal and human studies have shown an age-related β-adrenergic receptor (β-AR) dysfunction but the main mechanism involved is still unknown. Physiologically, when β-ARs are stimulated by agonists, the G protein-coupled receptor kinase 2 (GRK2) phosphorylates β-ARs that then become targets for binding of β-arrestins. This β-arrestin binding prevents their further coupling to the G protein, reducing the level of functional receptors and inducing their internalization. OBJECTIVE: In the present study we have tested the effects of β-arrestin-2 deletion on cardiac function and signaling in a murine model of aging. METHODS AND RESULTS: Genetically engineered, β-arrestin 2 KO and corresponding wild type (WT) male mice were enrolled to study physiological aging. We found that β-arrestin-2 deletion in aged mice is able to: a)improve LV contractility and dilatation b)enhance average and regional cardiac radial strain as well as radial SR during c)restore age-related cardiac β-AR desensitization d)reduce cardiac oxidative stress. CONCLUSIONS: Our study shows that β-arrestin 2 has a detrimental effect on the aged heart. β-arrestin 2 deletion reverses cardiac dysfunction and LV dilatation during aging. As a contributing mechanism, improved LV function is associated with restored β-AR density and reduced oxidative stress in aged hearts. Further, our results suggest β-arrestin 2 as a potential therapeutic target to limit age-related cardiac dysfunction.

博士
中國醫藥大學
老化醫學博士學位學程
102
According to the survey data of the Department of Health, Executive Yuan, ROC (Taiwan) in 101 years, it shows that cardiovascular disease has been in the second (9.1%) of the highest in the top ten leading causes of death, when coupled with related cardiovascular disease and its complications, such as cerebrovascular disease in the thrid (9.3%) and hypertension in the tenth (1.3%). Aging is an immutable law. The function of the heart is in the rate of 1% aging per year. With the advent of the aging society, we must study the serious problem of cardiovascular disease. The demonstrated roles of SIRT1, the mammalian counterpart of the yeast SIR2, reveal that SIRT1 regulates important cellular processes including anti-apoptosis, neuronal protection, cellular senescence, aging and longevity. In the previous studies in obesity in the laboratory, mice with high blood pressure and diabetes slowed down the performance of myocardial apoptosis through sports training. Therefore, this study designed a set of experiments with rats, aging and exercise, to obtain detail discussion of myocardial cells signaling transduction pathway changed. Three groups of different ages, 3 months, 12 months and 18 months old ages of mice were randomly divided into the aging groups (C3, A12 and A18) and exercise groups (E3, AE12 and AE18). Exercise training of swimming five times a week gradual increases from the first week of every 20 min to every 60 min for 12 weeks. Finally, after the complete of the sports training process, we used tissue sections to observe the type of organization (H & E stain), as well as the test of apoptosis (TUNEL Assays) and Western blotting to observe changes in the myocardial tissue and protein. Experimental results show that protein expression of cardiac myocyte apoptotic pathway increased in the aging groups (C3, A12 and A18), while the improvement in the exercise group. In the aging groups (C3, A12 and A18), the expression of the protein in the survival pathway increased with age to reduced performance, but in the exercise groups (E3, AE12 and AE18) increase access to improve performance. In addition, we did a preliminary study of myocardial apoptosis upstream SIRT regulation and the performance of the aging groups (C3, A12 and A18) was not obvious and On the contrary, there was much performance in the exercise groups (E3, AE12 and AE18) and it meant compensatory mechanism. On the other hand, we also obtain that aging induced cardiac fibrosis (C3, A12 and A18), via FGF2 / uPA / MMP2 pathway TGFβ1 / CTGF pathway and concentric cardiac hypertrophy via JNK / ERK1/2 / NFATc3 / GATA4 pathway to enhance cardiac injury, and exercise training (E3, AE12 and AE18) can reverse aging-induced cardiac injury. Therefore, we hope that a more in-depth study by our results of this study to investigate the mechanism of aging-induced heart injury.

Previous studies have shown that cardiac contractile function declines with age in ventricular myocytes from 24 month old males but not females. As estrogen modulates cardiac contractile function, age-dependent changes in estrogen may help preserve contraction in the aging female heart. The present study examined the effects of extreme old age as well as short and long term estrogen deprivation on cardiac contractile function. Cardiomyocytes were isolated from young adult (~7 mos) and senescent (~32 mos) C57BL/6 male and female mice, or from young adult (~8 mos) and aged (~24 mos) ovariectomized or sham control female mice. Myocytes were loaded with Fura-2 and paced at 2 Hz (37°C). Results showed that while Ca2+ dysregulation occurred in both senescent male and female mice, contractile function was preserved in female myocytes, even with extreme old age. This suggests that while aging causes Ca2+ dysregulation in males and females, contractile function is preserved in females. In other experiments, the effect of short ovariectomy on the excitation-contraction (EC) coupling pathway was investigated. Short term ovariectomy enhanced sarcoplasmic reticulum (SR) Ca2+ storage and release, by augmenting SR Ca2+ content and by increasing Ca2+ transients, Ca2+ sparks and EC-coupling gain. These findings suggest that estrogen may play a role in limiting SR Ca2+ loading and Ca2+ release in the female heart. The present study also investigated the effect of long term ovariectomy on the aging female heart. The results showed that long term ovariectomy enhanced Ca2+ influx and increased SR Ca2+ storage and release, but did not affect contractile function. This was due to a decrease in myofilament Ca2+ sensitivity with long term ovariectomy. However, enhanced Ca2+ levels did lead to larger spontaneous Ca2+ transients and greater abnormal electrical activity in the form of early afterdepolarizations. Together, the results suggest that aging as well as short and long term estrogen deprivation leads to Ca2+ dysregulation and spontaneous SR Ca2+ release. In the aging female heart, this Ca2+ dysregulation may increase the susceptibility to cardiovascular disease and dysfunction.

Left ventricular (LV) filling increases during exercise, but left atrial (LA) phasic function and its contribution to LV filling is poorly understood. Sixteen endurance-trained middle-aged males were studied at rest and during light (LE) and moderate (ME) intensity cycle-ergometry. Atrioventricular-plane displacement (AVPD) increased from rest to LE (from 14±2 mm to 18±2 mm, p<0.01), but did not increase further at ME. LA reservoir volume increased from rest to LE (from 32±8 mL to 40±10 mL, p<0.01). LA passive contribution increased at LE (from 21±5 mL to 27±8 mL, p<0.01), while LA active contribution increased from rest only at ME (from 12±5 mL to 23±9 mL, p<0.01). AVPD, and thus the longitudinal shortening of LV systole, contributes to LA filling primarily during LE, but is a limited mechanism beyond LE. These data suggest that LV filling appears to shift to a reliance on conduit function to increase LV filling at ME.