Segui questo link per vedere altri tipi di pubblicazioni sul tema: Sodium channels – Animal models.
Articoli di riviste sul tema "Sodium channels – Animal models"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 articoli di riviste per l'attività di ricerca sul tema "Sodium channels – Animal models".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi gli articoli di riviste di molte aree scientifiche e compila una bibliografia corretta.
1
Wood, John N., e Federico Iseppon. "Sodium channels". Brain and Neuroscience Advances 2 (gennaio 2018): 239821281881068. http://dx.doi.org/10.1177/2398212818810684.
Testo completoAbstract (sommario):
In 2000, with the completion of the human genome project, nine related channels were found to comprise the complete voltage-gated sodium gene family and they were renamed NaV1.1–NaV1.9. This millennial event reflected the extraordinary impact of molecular genetics on our understanding of electrical signalling in the nervous system. In this review, studies of animal electricity from the time of Galvani to the present day are described. The seminal experiments and models of Hodgkin and Huxley coupled with the discovery of the structure of DNA, the genetic code and the application of molecular genetics have resulted in an appreciation of the extraordinary diversity of sodium channels and their surprisingly broad repertoire of functions. In the present era, unsuspected roles for sodium channels in a huge range of pathologies have become apparent.
2
Crotti, Lia, Katja E. Odening e Michael C. Sanguinetti. "Heritable arrhythmias associated with abnormal function of cardiac potassium channels". Cardiovascular Research 116, n. 9 (19 maggio 2020): 1542–56. http://dx.doi.org/10.1093/cvr/cvaa068.
Testo completoAbstract (sommario):
Abstract Cardiomyocytes express a surprisingly large number of potassium channel types. The primary physiological functions of the currents conducted by these channels are to maintain the resting membrane potential and mediate action potential repolarization under basal conditions and in response to changes in the concentrations of intracellular sodium, calcium, and ATP/ADP. Here, we review the diversity and functional roles of cardiac potassium channels under normal conditions and how heritable mutations in the genes encoding these channels can lead to distinct arrhythmias. We briefly review atrial fibrillation and J-wave syndromes. For long and short QT syndromes, we describe their genetic basis, clinical manifestation, risk stratification, traditional and novel therapeutic approaches, as well as insights into disease mechanisms provided by animal and cellular models.
3
Hargus, Nicholas J., Aradhya Nigam, Edward H. Bertram e Manoj K. Patel. "Evidence for a role of Nav1.6 in facilitating increases in neuronal hyperexcitability during epileptogenesis". Journal of Neurophysiology 110, n. 5 (1 settembre 2013): 1144–57. http://dx.doi.org/10.1152/jn.00383.2013.
Testo completoAbstract (sommario):
During epileptogenesis a series of molecular and cellular events occur, culminating in an increase in neuronal excitability, leading to seizure initiation. The entorhinal cortex has been implicated in the generation of epileptic seizures in both humans and animal models of temporal lobe epilepsy. This hyperexcitability is due, in part, to proexcitatory changes in ion channel activity. Sodium channels play an important role in controlling neuronal excitability, and alterations in their activity could facilitate seizure initiation. We sought to investigate whether medial entorhinal cortex (mEC) layer II neurons become hyperexcitable and display proexcitatory behavior of Na channels during epileptogenesis. Experiments were conducted 7 days after electrical induction of status epilepticus (SE), a time point during the latent period of epileptogenesis and before the onset of seizures. mEC layer II stellate neurons from post-SE animals were hyperexcitable, eliciting action potentials at higher frequencies compared with control neurons. Na channel currents recorded from post-SE neurons revealed increases in Na current amplitudes, particularly persistent and resurgent currents, as well as depolarized shifts in inactivation parameters. Immunocytochemical studies revealed increases in voltage-gated Na (Nav) 1.6 isoform levels. The toxin 4,9-anhydro-tetrodotoxin, which has greater selectivity for Nav1.6 over other Na channel isoforms, suppressed neuronal hyperexcitability, reduced macroscopic Na currents, persistent and resurgent Na current densities, and abolished depolarized shifts in inactivation parameters in post-SE neurons. These studies support a potential role for Nav1.6 in facilitating the hyperexcitability of mEC layer II neurons during epileptogenesis.
4
Honoré, Per Hartvig, Anna Basnet, Pernille Kristensen, Lene Munkholm Andersen, Signe Neustrup, Pia Møllgaard, Laila Eljaja e Ole J. Bjerrum. "Predictive validity of pharmacologic interventions in animal models of neuropathic pain". Scandinavian Journal of Pain 2, n. 4 (1 ottobre 2011): 178–84. http://dx.doi.org/10.1016/j.sjpain.2011.06.002.
Testo completoAbstract (sommario):
AbstractIntroductionThe pathophysiologic and neurochemical characteristics of neuropathic pain must be considered in the search for new treatment targets. Breakthroughs in the understanding of the structural and biochemical changes in neuropathy have opened up possibilities to explore new treatment paradigms. However, long term sequels from the damage are still difficult to treat.Aim of the studyTo examine the validity of pharmacological treatments in humans and animals for neuropathic pain.MethodAn overview from the literature and own experiences of pharmacological treatments employed to interfere in pain behavior in different animal models was performed.ResultsThe treatment principles tested in animal models of neuropathic pain may have predictive validity for treatment of human neuropathies. Opioids, neurotransmitter blockers, drugs interfering with the prostaglandin syntheses as well as voltage gated sodium channel blockers and calcium channel blockers are treatment principles having efficacy and similar potency in humans and in animals. Alternative targets have been identified and have shown promising results in the validated animal models. Modulators of the glutamate system with an increased expression of glutamate re-uptake transporters, inhibition of pain promoters as nitric oxide and prostaglandins need further exploration. Modulation of cytokines and neurotrophins in neuropathic pain implies new targets for study. Further, a combination of different analgesic treatments may as well improve management of neuropathic pain, changing the benefit/risk ratio.ImplicationsNot surprisingly most pharmacologic principles that are tested in animal models of neuropathic pain are also found to be active in humans. Whereas many candidate drugs that were promising in animal models of neuropathic pain turned out not to be effective or too toxic in humans, animal models for neuropathic pain are still the best tools available to learn more about mechanisms of neuropathic pain. Better understanding of pathogenesis is the most hopeful approach to improve treatment of neuropathic pain.
5
Svajdova, S., e M. Brozmanova. "Regulation of Cough by Voltage-Gated Sodium Channels in Airway Sensory Nerves". Acta Medica Martiniana 18, n. 3 (1 dicembre 2018): 5–16. http://dx.doi.org/10.2478/acm-2018-0012.
Testo completoAbstract (sommario):
Abstract Chronic cough is a significant clinical problem in many patients. Current cough suppressant therapies are largely ineffective and have many dangerous adverse effects. Therefore, the identification of novel therapeutic targets and strategies for chronic cough treatment may lead to development of novel effective antitussive therapies with fewer adverse effects. The experimental research in the area of airway sensory nerves suggests that there are two main vagal afferent nerve subtypes that can directly activate cough – extrapulmonary airway C-fibres and Aδ-fibres (described as cough receptors) innervating the trachea. There are different receptors on the vagal nerve terminals that can trigger coughing, such as TRP channels and P2X2/3 receptors. However, in many patients with chronic respiratory diseases multiple activation of these receptors could be involved and it is also difficult to target these receptors. For that reason, a strategy that would inhibit cough-triggering nerve afferents regardless of activated receptors would be of great benefit. In recent years huge progress in understanding of voltage-gated sodium channels (NaVs) leads to a hypothesis that selective targeting of NaVs in airways may represent an effective treatment of pathological cough. The NaVs (NaV1.1 – NaV1.9) are essential for initiation and conduction of action potentials in these nerve fibres. Effective blocking of NaVs will prevent communication between airways and central nervous system and that would inhibit provoked cough irrespective to stimuli. This review provides an overview of airway afferent nerve subtypes that have been described in respiratory tract of human and in animal models. Moreover, the review highlights the current knowledge about cough, the sensory nerves involved in cough, and the voltage-gated sodium channels as a novel neural target in regulation of cough.
6
Takahashi, Hakuo. "Upregulation of the Renin-Angiotensin-Aldosterone-Ouabain System in the Brain Is the Core Mechanism in the Genesis of All Types of Hypertension". International Journal of Hypertension 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/242786.
Testo completoAbstract (sommario):
Basic research using animal models points to a causal role of the central nervous system in essential hypertension; however, since clinical research is technically difficult to perform, this connection has not been confirmed in humans. Recently, renal nerve ablation in humans proved to continuously decrease blood pressure in resistant hypertension. Furthermore, when electrical stimulation was continuously applied to the carotid baroreceptor nerve of human adults, their blood pressure lowered. These findings promoted the concept that the central nervous system may actually be involved in the pathogenesis of essential hypertension, which is closely associated with excess sodium intake. We have demonstrated that endogenous digitalis plays a key role in hypertension associated with excess sodium intake via sympathetic activation in rats. Increased sodium concentration inside the brain activates epithelial sodium channels and the renin-angiotensin-aldosterone system in the brain. Aldosterone releases ouabain from neurons in the paraventricular nucleus in the hypothalamus. Angiotensin II and aldosterone of peripheral origin reach the brain to augment sympathetic outflow. Collectively essential hypertension associated with excess sodium intake and obesity, renovascular hypertension, and primary aldosteronism and pseudoaldosteronism all seem to have a common cause originating from the central nervous system.
7
Tiwari, Swasti, Shahla Riazi e Carolyn A. Ecelbarger. "Insulin's impact on renal sodium transport and blood pressure in health, obesity, and diabetes". American Journal of Physiology-Renal Physiology 293, n. 4 (ottobre 2007): F974—F984. http://dx.doi.org/10.1152/ajprenal.00149.2007.
Testo completoAbstract (sommario):
Insulin has been shown to have antinatriuretic actions in humans and animal models. Moreover, endogenous hyperinsulinemia and insulin infusion have been correlated to increased blood pressure in some models. In this review, we present the current state of understanding with regard to the regulation of the major renal sodium transporters by insulin in the kidney. Several groups, using primarily cell culture, have demonstrated that insulin can directly increase activity of the epithelial sodium channel, the sodium-phosphate cotransporter, the sodium-hydrogen exchanger type III, and Na-K-ATPase. We and others have demonstrated alterations in the expression at the protein level of many of these same proteins with insulin infusion or in hyperinsulinemic models. We also discuss how this regulation is perturbed in type I and type II diabetes mellitus. Finally, we discuss a potential role for regulation of insulin receptor signaling in the kidney in contributing to sodium balance and blood pressure.
8
Liu, Zhonghua, Qi Zhu, Tianfu Cai, Ze Wu, Jing Li, Dan Li, Weiwen Ning et al. "260. Hainantoxin-III Inhibits Voltage-Gated Sodium Channel Nav 1.7 and Extenuates Inflammatory Pain in Animal Models". Toxicon 60, n. 2 (agosto 2012): 229–30. http://dx.doi.org/10.1016/j.toxicon.2012.04.261.
Testo completo
9
Bett, Glenna C. L. "Hormones and sex differences: changes in cardiac electrophysiology with pregnancy". Clinical Science 130, n. 10 (1 aprile 2016): 747–59. http://dx.doi.org/10.1042/cs20150710.
Testo completoAbstract (sommario):
Disruption of cardiac electrical activity resulting in palpitations and syncope is often an early symptom of pregnancy. Pregnancy is a time of dramatic and dynamic physiological and hormonal changes during which numerous demands are placed on the heart. These changes result in electrical remodelling which can be detected as changes in the electrocardiogram (ECG). This gestational remodelling is a very under-researched area. There are no systematic large studies powered to determine changes in the ECG from pre-pregnancy, through gestation, and into the postpartum period. The large variability between patients and the dynamic nature of pregnancy hampers interpretation of smaller studies, but some facts are consistent. Gestational cardiac hypertrophy and a physical shift of the heart contribute to changes in the ECG. There are also electrical changes such as an increased heart rate and lengthening of the QT interval. There is an increased susceptibility to arrhythmias during pregnancy and the postpartum period. Some changes in the ECG are clearly the result of changes in ion channel expression and behaviour, but little is known about the ionic basis for this electrical remodelling. Most information comes from animal models, and implicates changes in the delayed-rectifier channels. However, it is likely that there are additional roles for sodium channels as well as changes in calcium homoeostasis. The changes in the electrical profile of the heart during pregnancy and the postpartum period have clear implications for the safety of pregnant women, but the field remains relatively undeveloped.
10
Góra, Małgorzata, Anna Czopek, Anna Rapacz, Anna Dziubina, Monika Głuch-Lutwin, Barbara Mordyl e Jolanta Obniska. "Synthesis, Anticonvulsant and Antinociceptive Activity of New Hybrid Compounds: Derivatives of 3-(3-Methylthiophen-2-yl)-pyrrolidine-2,5-dione". International Journal of Molecular Sciences 21, n. 16 (11 agosto 2020): 5750. http://dx.doi.org/10.3390/ijms21165750.
Testo completoAbstract (sommario):
The present study aimed to design and synthesize a new series of hybrid compounds with pyrrolidine-2,5-dione and thiophene rings in the structure as potential anticonvulsant and antinociceptive agents. For this purpose, we obtained a series of new compounds and evaluated their anticonvulsant activity in animal models of epilepsy (maximal electroshock (MES), psychomotor (6 Hz), and subcutaneous pentylenetetrazole (scPTZ) seizure tests). To determine the mechanism of action of the most active anticonvulsant compounds (3, 4, 6, 9), their influence on the voltage-gated sodium and calcium channels as well as GABA transporter (GAT) was assessed. The most promising compound 3-(3-methylthiophen-2-yl)-1-(3-morpholinopropyl)pyrrolidine-2,5-dione hydrochloride (4) showed higher ED50 value than those of the reference drugs: valproic acid (VPA) and ethosuximide (ETX) (62.14 mg/kg vs. 252.7 mg/kg (VPA) in the MES test, and 75.59 mg/kg vs. 130.6 mg/kg (VPA) and 221.7 mg/kg (ETX) in the 6 Hz test, respectively). Moreover, in vitro studies of compound 4 showed moderate but balanced inhibition of the neuronal voltage-sensitive sodium (site 2) and L-type calcium channels. Additionally, the antinociceptive activity of the most active compounds (3, 4, 6, 9) was also evaluated in the hot plate test and writhing tests, and their hepatotoxic properties in HepG2 cells were also investigated. To determine the possible mechanism of the analgesic effect of compounds 3, 6, and 9, the affinity for the TRPV1 receptor was investigated.
11
Martinez-Lavin, Manuel. "Fibromyalgia: When Distress Becomes (Un)sympathetic Pain". Pain Research and Treatment 2012 (19 settembre 2012): 1–6. http://dx.doi.org/10.1155/2012/981565.
Testo completoAbstract (sommario):
Fibromyalgia is a painful stress-related disorder. A key issue in fibromyalgia research is to investigate how distress could be converted into pain. The sympathetic nervous system is the main element of the stress response system. In animal models, physical trauma, infection, or distressing noise can induce abnormal connections between the sympathetic nervous system and the nociceptive system. Dorsal root ganglia sodium channels facilitate this type of sympathetic pain. Similar mechanisms may operate in fibromyalgia. Signs of sympathetic hyperactivity have been described in this condition. Genetic factors and/or distressful lifestyle may lead to this state of sympathetic hyperactivity. Trauma and infection are recognized fibromyalgia triggers. Women who suffer from fibromyalgia have catecholamine-evoked pain. Sympathetic dysfunction may also explain nonpain-related fibromyalgia symptoms. In conclusion, in fibromyalgia, distress could be converted into pain through forced hyperactivity of the sympathetic component of the stress response system.
12
Bigiani, Albertino. "Does ENaC Work as Sodium Taste Receptor in Humans?" Nutrients 12, n. 4 (24 aprile 2020): 1195. http://dx.doi.org/10.3390/nu12041195.
Testo completoAbstract (sommario):
Taste reception is fundamental for the proper selection of food and beverages. Among the several chemicals recognized by the human taste system, sodium ions (Na+) are of particular relevance. Na+ represents the main extracellular cation and is a key factor in many physiological processes. Na+ elicits a specific sensation, called salty taste, and low-medium concentrations of table salt (NaCl, the common sodium-containing chemical we use to season foods) are perceived as pleasant and appetitive. How we detect this cation in foodstuffs is scarcely understood. In animal models, such as the mouse and the rat, the epithelial sodium channel (ENaC) has been proposed as a key protein for recognizing Na+ and for mediating preference responses to low-medium salt concentrations. Here, I will review our current understanding regarding the possible involvement of ENaC in the detection of food Na+ by the human taste system.
13
Bankir, Lise, Daniel G. Bichet e Nadine Bouby. "Vasopressin V2 receptors, ENaC, and sodium reabsorption: a risk factor for hypertension?" American Journal of Physiology-Renal Physiology 299, n. 5 (novembre 2010): F917—F928. http://dx.doi.org/10.1152/ajprenal.00413.2010.
Testo completoAbstract (sommario):
Excessive sodium reabsorption by the kidney has long been known to participate in the pathogenesis of some forms of hypertension. In the kidney, the final control of NaCl reabsorption takes place in the distal nephron through the amiloride-sensitive epithelial sodium channel (ENaC). Liddle's syndrome, an inherited form of hypertension due to gain-of-function mutations in the genes coding for ENaC subunits, has demonstrated the key role of this channel in the sodium balance. Although aldosterone is classically thought to be the main hormone regulating ENaC activity, several studies in animal models and in humans highlight the important effect of vasopressin on ENaC regulation and sodium transport. This review summarizes the effect of vasopressin V2 receptor stimulation on ENaC activity and sodium excretion in vivo. Moreover, we report the experimental and clinical data demonstrating the role of renal ENaC in water conservation at the expense of a reduced ability to excrete sodium. Acute administration of the selective V2 receptor agonist dDAVP not only increases urine osmolality and reduces urine flow rate but also reduces sodium excretion in rats and humans. Chronic V2 receptor stimulation increases blood pressure in rats, and a significant correlation was found between blood pressure and urine concentration in healthy humans. This led us to discuss how excessive vasopressin-dependent ENaC stimulation could be a risk factor for sodium retention and resulting increase in blood pressure.
14
Cohan, Stanley L., David J. Redmond, Mei Chen, Dahlia Wilson e Philip Cyr. "Flunarizine Blocks Elevation of Free Cytosolic Calcium in Synaptosomes following Sustained Depolarization". Journal of Cerebral Blood Flow & Metabolism 13, n. 6 (novembre 1993): 947–54. http://dx.doi.org/10.1038/jcbfm.1993.118.
Testo completoAbstract (sommario):
Gerbil cerebral cortical synaptosomes loaded with the fluorescent calcium probe FURA-2 were used to study depolarization-induced presynaptic cytosolic free calcium concentration, as an in vitro model of cerebral ischemia. The depolarization-induced increase in intrasynaptosomal cytosolic free calcium concentration is not sodium-dependent or sodium channel-dependent and may be due to an influx of extrasynaptosomal calcium resulting from a cadmium- and omega-conotoxin-sensitive, nickel-, nifedipine-, and nimodipine-insensitive voltage-regulated channel. The depolarization-induced increase in intrasynaptosomal free cytosolic calcium concentration is also inhibited by flunarizine, a calcium antagonist that has protective effects in animal models of cerebral anoxia and ischemia. Our results suggest that presynaptic calcium uptake following depolarization may be mediated in part by an N-type channel. Flunarizine may block presynaptic calcium accumulation, in part, by blocking this N-type channel; this blockade may be just one of several mechanisms by which flunarizine exerts protective effects following cerebral ischemia.
15
Dewis, Mark L., Tam-Hao T. Phan, ZuoJun Ren, Xuanyu Meng, Meng Cui, Shobha Mummalaneni, Mee-Ra Rhyu, John A. DeSimone e Vijay Lyall. "N-geranyl cyclopropyl-carboximide modulates salty and umami taste in humans and animal models". Journal of Neurophysiology 109, n. 4 (15 febbraio 2013): 1078–90. http://dx.doi.org/10.1152/jn.00124.2012.
Testo completoAbstract (sommario):
Effects of N-geranyl cyclopropylcarboxamide (NGCC) and four structurally related compounds ( N-cyclopropyl E2,Z6-nonadienamide, N-geranyl isobutanamide, N-geranyl 2-methylbutanamide, and allyl N-geranyl carbamate) were evaluated on the chorda tympani (CT) nerve response to NaCl and monosodium glutamate (MSG) in rats and wild-type (WT) and TRPV1 knockout (KO) mice and on human salty and umami taste intensity. NGCC enhanced the rat CT response to 100 mM NaCl + 5 μM benzamil (Bz; an epithelial Na+ channel blocker) between 1 and 2.5 μM and inhibited it above 5 μM. N-(3-methoxyphenyl)-4-chlorocinnamid (SB-366791, a TRPV1t blocker) inhibited the NaCl+Bz CT response in the absence and presence of NGCC. Unlike the WT mice, no NaCl+Bz CT response was observed in TRPV1 KO mice in the absence or presence of NGCC. NGCC enhanced human salt taste intensity of fish soup stock containing 60 mM NaCl at 5 and 10 μM and decreased it at 25 μM. Rat CT responses to NaCl+Bz and human salt sensory perception were not affected by the above four structurally related compounds. Above 10 μM, NGCC increased the CT response to MSG+Bz+SB-366791 and maximally enhanced the response between 40 and 60 μM. Increasing taste cell Ca2+ inhibited the NGCC-induced increase but not the inosine monophosphate-induced increase in glutamate response. Addition of 45 μM NGCC to chicken broth containing 60 mM sodium enhanced the human umami taste intensity. Thus, depending upon its concentration, NGCC modulates salt taste by interacting with the putative TRPV1t-dependent salt taste receptor and umami taste by interacting with a Ca2+-dependent transduction pathway.
16
Fritz, Elsa, Pamela Izaurieta, Alexandra Weiss, Franco R. Mir, Patricio Rojas, David Gonzalez, Fabiola Rojas, Robert H. Brown, Rodolfo Madrid e Brigitte van Zundert. "Mutant SOD1-expressing astrocytes release toxic factors that trigger motoneuron death by inducing hyperexcitability". Journal of Neurophysiology 109, n. 11 (1 giugno 2013): 2803–14. http://dx.doi.org/10.1152/jn.00500.2012.
Testo completoAbstract (sommario):
Amyotrophic lateral sclerosis (ALS) is a devastating paralytic disorder caused by dysfunction and degeneration of motoneurons starting in adulthood. Recent studies using cell or animal models document that astrocytes expressing disease-causing mutations of human superoxide dismutase 1 (hSOD1) contribute to the pathogenesis of ALS by releasing a neurotoxic factor(s). Neither the mechanism by which this neurotoxic factor induces motoneuron death nor its cellular site of action has been elucidated. Here we show that acute exposure of primary wild-type spinal cord cultures to conditioned medium derived from astrocytes expressing mutant SOD1 (ACM-hSOD1G93A) increases persistent sodium inward currents (PCNa), repetitive firing, and intracellular calcium transients, leading to specific motoneuron death days later. In contrast to TTX, which paradoxically increased twofold the amplitude of calcium transients and killed motoneurons, reduction of hyperexcitability by other specific (mexiletine) and nonspecific (spermidine and riluzole) blockers of voltage-sensitive sodium (Nav) channels restored basal calcium transients and prevented motoneuron death induced by ACM-hSOD1G93A. These findings suggest that riluzole, the only FDA-approved drug with known benefits for ALS patients, acts by inhibiting hyperexcitability. Together, our data document that a critical element mediating the non-cell-autonomous toxicity of ACM-hSOD1G93A on motoneurons is increased excitability, an observation with direct implications for therapy of ALS.
17
Gomez-Sanchez, E. P., e C. E. Gomez-Sanchez. "Effect of central amiloride infusion on mineralocorticoid hypertension". American Journal of Physiology-Endocrinology and Metabolism 267, n. 5 (1 novembre 1994): E754—E758. http://dx.doi.org/10.1152/ajpendo.1994.267.5.e754.
Testo completoAbstract (sommario):
There is strong evidence from different types of studies, including the discrete infusion of agonists and antagonists and ablation of specific brain areas or transmitter-type neurons, that mineralocorticoids, in excess, act in the brain to elevate blood pressure. Aldosterone enhances the entry of Na+ through amiloride-sensitive Na+ channels in some mineralocorticoid-sensitive transport epithelial cells. To define possible cellular mechanisms involved in central mineralocorticoid action, benzamil, an amiloride analogue with selective affinity for the Na+ channel, was continuously infused intracerebroventricularly in three mineralocorticoid-dependent hypertension models in Sprague-Dawley rats, the continuous subcutaneous infusion of aldosterone, the intracerebroventricular infusion of aldosterone, and the ingestion of carbenoxolone, a synthetic licorice analogue. The intracerebroventricular infusion of 0.3 and 0.5 micrograms/h of benzamil, doses that did not have an adverse effect on growth and that had no effect on the blood pressure when infused subcutaneously, prevented the increase in blood pressure in these models. The infusion of these levels of benzamil had no effect on urine volume even in those animals in which it prevented an increase in blood pressure. These data suggest that the central effects of mineralocorticoids on blood pressure are mediated, at least in part, by the effects of mineralocorticoids on amiloride-sensitive sodium transport.
18
Zhong, Beihua, Shuangtao Ma e Donna H. Wang. "Ablation of TRPV1 Abolishes Salicylate-Induced Sympathetic Activity Suppression and Exacerbates Salicylate-Induced Renal Dysfunction in Diet-Induced Obesity". Cells 10, n. 5 (18 maggio 2021): 1234. http://dx.doi.org/10.3390/cells10051234.
Testo completoAbstract (sommario):
Sodium salicylate (SA), a cyclooxygenase inhibitor, has been shown to increase insulin sensitivity and to suppress inflammation in obese patients and animal models. Transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel expressed in afferent nerve fibers. Cyclooxygenase-derived prostaglandins are involved in the activation and sensitization of TRPV1. This study tested whether the metabolic and renal effects of SA were mediated by the TRPV1 channel. Wild-type (WT) and TRPV1−/− mice were fed a Western diet (WD) for 4 months and received SA infusion (120mg/kg/day) or vehicle for the last 4 weeks of WD feeding. SA treatment significantly increased blood pressure in WD-fed TRPV1−/− mice (p < 0.05) but not in WD-fed WT mice. Similarly, SA impaired renal blood flow in TRPV1−/− mice (p < 0.05) but not in WT mice. SA improved insulin and glucose tolerance in both WT and TRPV1−/− mice on WD (all p < 0.05). In addition, SA reduced renal p65 and urinary prostaglandin E2, prostaglandin F1α, and interleukin-6 in both WT and TRPV1−/− mice (all p < 0.05). SA decreased urine noradrenaline levels, increased afferent renal nerve activity, and improved baroreflex sensitivity in WT mice (all p < 0.05) but not in TRPV1−/− mice. Importantly, SA increased serum creatinine and urine kidney injury molecule-1 levels and decreased the glomerular filtration rate in obese WT mice (all p < 0.05), and these detrimental effects were significantly exacerbated in obese TRPV1−/− mice (all p < 0.05). Lastly, SA treatment increased urine albumin levels in TRPV1−/− mice (p < 0.05) but not in WT mice. Taken together, SA-elicited metabolic benefits and anti-inflammatory effects are independent of TRPV1, while SA-induced sympathetic suppression is dependent on TRPV1 channels. SA-induced renal dysfunction is dependent on intact TRPV1 channels. These findings suggest that SA needs to be cautiously used in patients with obesity or diabetes, as SA-induced renal dysfunction may be exacerbated due to impaired TRPV1 in obese and diabetic patients.
19
Nickolaus, Peter, Birgit Jung, Juan Sabater, Samuel Constant e Abhya Gupta. "Preclinical evaluation of the epithelial sodium channel inhibitor BI 1265162 for treatment of cystic fibrosis". ERJ Open Research 6, n. 4 (ottobre 2020): 00429–2020. http://dx.doi.org/10.1183/23120541.00429-2020.
Testo completoAbstract (sommario):
BackgroundEpithelial sodium channel (ENaC) is an important regulator of airway surface liquid volume; ENaC is hyperactivated in cystic fibrosis (CF). ENaC inhibition is a potential therapeutic target for CF. Here, we report in vitro and in vivo results for BI 1265162, an inhaled ENaC inhibitor currently in Phase II clinical development, administered via the Respimat® Soft Mist™ inhaler.MethodsIn vitro inhibition of sodium ion (Na+) transport by BI 1265162 was tested in mouse renal collecting duct cells (M1) and human bronchial epithelial cells (NCI-H441); inhibition of water transport was measured using M1 cells. In vivo inhibition of liquid absorption from rat airway epithelium and acceleration of mucociliary clearance (MCC) in sheep lungs were assessed. Fully differentiated normal and CF human epithelium was used to measure the effect of BI 1265162 with or without ivacaftor and lumacaftor on water transport and MCC.ResultsBI 1265162 dose-dependently inhibited Na+ transport and decreased water resorption in cell line models. BI 1265162 reduced liquid absorption in rat lungs and increased MCC in sheep. No effects on renal function were seen in the animal models. BI 1265162 alone and in combination with CF transmembrane conductance regulator (CFTR) modulators decreased water transport and increased MCC in both normal and CF airway human epithelial models and also increased the effects of CFTR modulators in CF epithelium to reach the effect size seen in healthy epithelium with ivacaftor/lumacaftor alone.ConclusionThese results demonstrate the potential of BI 1265162 as a mutation agnostic, ENaC-inhibitor-based therapy for CF.
20
Galli, A., L. J. DeFelice, B. J. Duke, K. R. Moore e R. D. Blakely. "Sodium-dependent norepinephrine-induced currents in norepinephrine-transporter-transfected HEK-293 cells blocked by cocaine and antidepressants." Journal of Experimental Biology 198, n. 10 (1 ottobre 1995): 2197–212. http://dx.doi.org/10.1242/jeb.198.10.2197.
Testo completoAbstract (sommario):
Transport of norepinephrine (NE+) by cocaine- and antidepressant-sensitive transporters in presynaptic terminals is predicted to involve the cotransport of Na+ and Cl-, resulting in a net movement of charge per transport cycle. To explore the relationship between catecholamine transport and ion permeation through the NE transporter, we established a human norepinephrine transporter (hNET) cell line suitable for biochemical analysis and patch-clamp recording. Stable transfection of hNET cDNA into HEK-293 (human embryonic kidney) cells results in lines exhibiting (1) a high number of transporter copies per cell (10(6)), as detected by radioligand binding and hNET-specific antibodies, (2) high-affinity, Na(+)-dependent transport of NE, and (3) inhibitor sensitivities similar to those of native membranes. Whole-cell voltage-clamp of hNET-293 cells reveals NE-induced, Na(+)-dependent currents blocked by antidepressants and cocaine that are absent in parental cells. In addition to NE-dependent currents, transfected cells posses an NE-independent mode of charge movement mediated by hNET. hNET antagonists without effect in non-transfected cells abolish both NE-dependent and NE-independent modes of charge movement in transfected cells. The magnitude of NE-dependent currents in these cells exceeds the expectations of simple carrier models using previous estimates of transport rates. To explain our observations, we propose that hNETs function as ion-gated ligand channels with an indefinite stoichiometry relating ion flux to NE transport. In this view, external Na+ and NE bind to the transporter with finite affinities in a cooperative fashion. However, coupled transport may not predict the magnitude or the kinetics of the total current through the transporter. We propose instead that Na+ gates NE transport and also the parallel inward flux of an indeterminate number of ions through a channel-like pore.
21
Shi, Xuan-Zheng, John H. Winston e Sushil K. Sarna. "Differential immune and genetic responses in rat models of Crohn's colitis and ulcerative colitis". American Journal of Physiology-Gastrointestinal and Liver Physiology 300, n. 1 (gennaio 2011): G41—G51. http://dx.doi.org/10.1152/ajpgi.00358.2010.
Testo completoAbstract (sommario):
Crohn's disease and ulcerative colitis are clinically, immunologically, and morphologically distinct forms of inflammatory bowel disease (IBD). However, smooth muscle function is impaired similarly in both diseases, resulting in diarrhea. We tested the hypothesis that differential cellular, genetic, and immunological mechanisms mediate smooth muscle dysfunction in two animal models believed to represent the two diseases. We used the rat models of trinitrobenzene sulfonic acid (TNBS)- and dextran sodium sulfate (DSS)-induced colonic inflammations, which closely mimic the clinical and morphological features of Crohn's disease and ulcerative colitis, respectively. DSS inflammation induced oxidative stress initially in mucosa/submucosa, which then propagated to the muscularis externa to impair smooth muscle function. The muscularis externa showed no increase of cytokines/chemokines. On the other hand, TNBS inflammation almost simultaneously induced oxidative stress, recruited or activated immune cells, and generated cytokines/chemokines in both mucosa/submucosa and muscularis externa. The generation of cytokines/chemokines did not correlate with the recruitment and activation of immune cells. Consequently, the impairment of smooth muscle function in DSS inflammation was primarily due to oxidative stress, whereas that in TNBS inflammation was due to both oxidative stress and proinflammatory cytokines. The impairment of smooth muscle function in DSS inflammation was due to suppression of Gαq protein of the excitation-contraction coupling. In TNBS inflammation, it was due to suppression of the α1C1b subunit of Cav1.2b channels, CPI-17 and Gαq. TNBS inflammation increased IGF-1 and TGF-β time dependently in the muscularis externa. IGF-1 induced smooth muscle hyperplasia; both IGF-1 and TGF-β induced hypertrophy. In conclusion, both TNBS and DSS induce transmural inflammation, albeit with different types of inflammatory mediators. The recruitment or activation of immune cells does not correlate directly with the intensity of generation of inflammatory mediators. The inflammatory mediators in TNBS and DSS inflammations target different genes to impair smooth muscle function.
22
González-Cano, Rafael, M. Carmen Ruiz-Cantero, Miriam Santos-Caballero, Carlos Gómez-Navas, Miguel Á. Tejada e Francisco R. Nieto. "Tetrodotoxin, a Potential Drug for Neuropathic and Cancer Pain Relief?" Toxins 13, n. 7 (12 luglio 2021): 483. http://dx.doi.org/10.3390/toxins13070483.
Testo completoAbstract (sommario):
Tetrodotoxin (TTX) is a potent neurotoxin found mainly in puffer fish and other marine and terrestrial animals. TTX blocks voltage-gated sodium channels (VGSCs) which are typically classified as TTX-sensitive or TTX-resistant channels. VGSCs play a key role in pain signaling and some TTX-sensitive VGSCs are highly expressed by adult primary sensory neurons. During pathological pain conditions, such as neuropathic pain, upregulation of some TTX-sensitive VGSCs, including the massive re-expression of the embryonic VGSC subtype NaV1.3 in adult primary sensory neurons, contribute to painful hypersensitization. In addition, people with loss-of-function mutations in the VGSC subtype NaV1.7 present congenital insensitive to pain. TTX displays a prominent analgesic effect in several models of neuropathic pain in rodents. According to this promising preclinical evidence, TTX is currently under clinical development for chemo-therapy-induced neuropathic pain and cancer-related pain. This review focuses primarily on the preclinical and clinical evidence that support a potential analgesic role for TTX in these pain states. In addition, we also analyze the main toxic effects that this neurotoxin produces when it is administered at therapeutic doses, and the therapeutic potential to alleviate neuropathic pain of other natural toxins that selectively block TTX-sensitive VGSCs.
23
Alborghetti, Marika, e Ferdinando Nicoletti. "Different Generations of Type-B Monoamine Oxidase Inhibitors in Parkinson’s Disease: From Bench to Bedside". Current Neuropharmacology 17, n. 9 (22 agosto 2019): 861–73. http://dx.doi.org/10.2174/1570159x16666180830100754.
Testo completoAbstract (sommario):
Three inhibitors of type-B monoamine oxidase (MAOB), selegiline, rasagiline, and safinamide, are used for the treatment of Parkinson’s disease (PD). All three drugs improve motor signs of PD, and are effective in reducing motor fluctuations in patients undergoing long-term L-DOPA treatment. The effect of MAOB inhibitors on non-motor symptoms is not uniform and may not be class-related. Selegiline and rasagiline are irreversible inhibitors forming a covalent bond within the active site of MAOB. In contrast, safinamide is a reversible MAOB inhibitor, and also inhibits voltage- sensitive sodium channels and glutamate release. Safinamide is the prototype of a new generation of multi-active MAOB inhibitors, which includes the antiepileptic drug, zonisamide. Inhibition of MAOB-mediated dopamine metabolism largely accounts for the antiparkinsonian effect of the three drugs. Dopamine metabolism by MAOB generates reactive oxygen species, which contribute to nigro-striatal degeneration. Among all antiparkinsonian agents, MAOB inhibitors are those with the greatest neuroprotective potential because of inhibition of dopamine metabolism, induction of neurotrophic factors, and, in the case of safinamide, inhibition of glutamate release. The recent development of new experimental animal models that more closely mimic the progressive neurodegeneration associated with PD will allow to test the hypothesis that MAOB inhibitors may slow the progression of PD.
24
Clauss, Wolfgang G. "Epithelial transport and osmoregulation in annelids". Canadian Journal of Zoology 79, n. 2 (1 febbraio 2001): 192–203. http://dx.doi.org/10.1139/z00-200.
Testo completoAbstract (sommario):
Epithelial transport related to osmoregulation has so far not been extensively investigated in annelids. Compared with the large body of information about ion transport across crustacean or insect epithelia, only a few studies have been done with isolated preparations of annelids, using the body wall of marine polychaetes or Hirudinea. Nephridial function and general body homeostasis have received more attention, and have probably been best investigated in Hirudinea. With recent advances in the molecular physiology of epithelial transport systems in vertebrates, the cloning of various transporters and ion channels, and the considerable number of osmoregulatory peptides that have now been found and analyzed from annelids, it should now be possible, and is timely, to conduct functional studies on individual selected epithelial preparations or isolated cells from annelids. Such studies may be important for establishing useful models with somewhat less complexity than mammalian systems. For example, annelids lack aldosterone, an important osmoregulatory hormone, which is a key factor in the regulation of sodium reabsorption in vertebrates. Therefore, not only would such studies contribute to annelid physiology, but they would be important in a broader sense for understanding osmoregulation and its evolution. They should also facilitate the discovery and investigation of new specific regulatory pathways.
25
Kawashiri, Takehiro, Keisuke Mine, Daisuke Kobayashi, Mizuki Inoue, Soichiro Ushio, Mayako Uchida, Nobuaki Egashira e Takao Shimazoe. "Therapeutic Agents for Oxaliplatin-Induced Peripheral Neuropathy; Experimental and Clinical Evidence". International Journal of Molecular Sciences 22, n. 3 (30 gennaio 2021): 1393. http://dx.doi.org/10.3390/ijms22031393.
Testo completoAbstract (sommario):
Oxaliplatin is an essential drug in the chemotherapy of colorectal, gastric, and pancreatic cancers, but it frequently causes peripheral neuropathy as a dose-limiting factor. So far, animal models of oxaliplatin-induced peripheral neuropathy have been established. The mechanisms of development of neuropathy induced by oxaliplatin have been elucidated, and many drugs and agents have been proven to have neuroprotective effects in basic studies. In addition, some of these drugs have been validated in clinical studies for their inhibitory effects on neuropathy. In this review, we summarize the basic and clinical evidence for the therapeutic effects of oxaliplatin. In basic research, there are many reports of neuropathy inhibitors that target oxidative stress, inflammatory response, sodium channel, transient receptor potential (TRP) channel, glutamate nervous system, and monoamine nervous system. Alternatively, very few drugs have clearly demonstrated the efficacy for oxaliplatin-induced peripheral neuropathy in clinical trials. It is important to activate translational research in order to translate basic research into clinical research.
26
Voskobiynyk, Yuliya, Gopal Battu, Stephanie A. Felker, J. Nicholas Cochran, Megan P. Newton, Laura J. Lambert, Robert A. Kesterson et al. "Aberrant regulation of a poison exon caused by a non-coding variant in a mouse model of Scn1a-associated epileptic encephalopathy". PLOS Genetics 17, n. 1 (7 gennaio 2021): e1009195. http://dx.doi.org/10.1371/journal.pgen.1009195.
Testo completoAbstract (sommario):
Dravet syndrome (DS) is a developmental and epileptic encephalopathy that results from mutations in the Nav1.1 sodium channel encoded by SCN1A. Most known DS-causing mutations are in coding regions of SCN1A, but we recently identified several disease-associated SCN1A mutations in intron 20 that are within or near to a cryptic and evolutionarily conserved “poison” exon, 20N, whose inclusion is predicted to lead to transcript degradation. However, it is not clear how these intron 20 variants alter SCN1A expression or DS pathophysiology in an organismal context, nor is it clear how exon 20N is regulated in a tissue-specific and developmental context. We address those questions here by generating an animal model of our index case, NM_006920.4(SCN1A):c.3969+2451G>C, using gene editing to create the orthologous mutation in laboratory mice. Scn1a heterozygous knock-in (+/KI) mice exhibited an ~50% reduction in brain Scn1a mRNA and Nav1.1 protein levels, together with characteristics observed in other DS mouse models, including premature mortality, seizures, and hyperactivity. In brain tissue from adult Scn1a +/+ animals, quantitative RT-PCR assays indicated that ~1% of Scn1a mRNA included exon 20N, while brain tissue from Scn1a +/KI mice exhibited an ~5-fold increase in the extent of exon 20N inclusion. We investigated the extent of exon 20N inclusion in brain during normal fetal development in RNA-seq data and discovered that levels of inclusion were ~70% at E14.5, declining progressively to ~10% postnatally. A similar pattern exists for the homologous sodium channel Nav1.6, encoded by Scn8a. For both genes, there is an inverse relationship between the level of functional transcript and the extent of poison exon inclusion. Taken together, our findings suggest that poison exon usage by Scn1a and Scn8a is a strategy to regulate channel expression during normal brain development, and that mutations recapitulating a fetal-like pattern of splicing cause reduced channel expression and epileptic encephalopathy.
27
Park, David S., Akshay Shekhar, John Santucci, Gabriel Redel-Traub, Sergio Solinas, Shana Mintz, Xianming Lin et al. "Ionic Mechanisms of Impulse Propagation Failure in the FHF2-Deficient Heart". Circulation Research 127, n. 12 (4 dicembre 2020): 1536–48. http://dx.doi.org/10.1161/circresaha.120.317349.
Testo completoAbstract (sommario):
Rationale: FHFs (fibroblast growth factor homologous factors) are key regulators of sodium channel (Na V ) inactivation. Mutations in these critical proteins have been implicated in human diseases including Brugada syndrome, idiopathic ventricular arrhythmias, and epileptic encephalopathy. The underlying ionic mechanisms by which reduced Na v availability in Fhf2 knockout ( Fhf2 KO ) mice predisposes to abnormal excitability at the tissue level are not well defined. Objective: Using animal models and theoretical multicellular linear strands, we examined how FHF2 orchestrates the interdependency of sodium, calcium, and gap junctional conductances to safeguard cardiac conduction. Methods and Results: Fhf2 KO mice were challenged by reducing calcium conductance (gCa V ) using verapamil or by reducing gap junctional conductance (Gj) using carbenoxolone or by backcrossing into a cardiomyocyte-specific Cx43 (connexin 43) heterozygous background. All conditions produced conduction block in Fhf2 KO mice, with Fhf2 wild-type ( Fhf2 WT ) mice showing normal impulse propagation. To explore the ionic mechanisms of block in Fhf2 KO hearts, multicellular linear strand models incorporating FHF2-deficient Na v inactivation properties were constructed and faithfully recapitulated conduction abnormalities seen in mutant hearts. The mechanisms of conduction block in mutant strands with reduced gCa V or diminished Gj are very different. Enhanced Na v inactivation due to FHF2 deficiency shifts dependence onto calcium current (I Ca ) to sustain electrotonic driving force, axial current flow, and action potential (AP) generation from cell-to-cell. In the setting of diminished Gj, slower charging time from upstream cells conspires with accelerated Na v inactivation in mutant strands to prevent sufficient downstream cell charging for AP propagation. Conclusions: FHF2-dependent effects on Na v inactivation ensure adequate sodium current (I Na ) reserve to safeguard against numerous threats to reliable cardiac impulse propagation.
28
Schultz, Jacob G., Stine Andersen, Asger Andersen, Jens Erik Nielsen-Kudsk e Jan M. Nielsen. "Evaluation of cardiac electrophysiological properties in an experimental model of right ventricular hypertrophy and failure". Cardiology in the Young 26, n. 3 (14 aprile 2015): 451–58. http://dx.doi.org/10.1017/s1047951115000402.
Testo completoAbstract (sommario):
AbstractBackgroundMalignant arrhythmias are a major cause of sudden cardiac death in adults with congenital heart disease. We developed a model to serially investigate electrophysiological properties in an animal model of right ventricular hypertrophy and failure.MethodWe created models of compensated (cHF; n=11) and decompensated (dHF; n=11) right ventricular failure in Wistar rats by pulmonary trunk banding. Healthy controls underwent sham operation (Control; n=13). Surface electrocardiography was recorded from extremities, and inducibility of ventricular tachycardia was evaluated in vivo by programmed stimulation. Isolated right ventricular myocardium was analysed for mRNA expression of selected genes.ResultsBanding caused an increased mRNA expression of both connexin 43 and the voltage-gated sodium channel 1.5, as well as a prolongation of PQ, QRS and QTc intervals. Ventricular tachycardia was induced in the majority of banded animals compared with none in the healthy control group. No differences were found between the two degrees of failure in neither the electrophysiological parameters nor inducibility.ConclusionsThe electrophysiological properties of rat hearts subjected to pulmonary trunk banding were significantly changed with increased susceptibility to ventricular tachycardia, but no differences were found between compensated and decompensated right ventricular failure. Furthermore, we demonstrate that in vivo electrophysiological evaluation is a sensitive method to characterise the cardiac electric phenotype in an experimental rat model.
29
Kögler, Gesine, Sandra Sensken, Judith A. Airey, Thorsten Trapp, Markus Müschen, Niklas Feldhahn, Stefanie Liedtke et al. "A New Human Somatic Stem Cell from Placental Cord Blood with Intrinsic Pluripotent Differentiation Potential". Journal of Experimental Medicine 200, n. 2 (19 luglio 2004): 123–35. http://dx.doi.org/10.1084/jem.20040440.
Testo completoAbstract (sommario):
Here a new, intrinsically pluripotent, CD45-negative population from human cord blood, termed unrestricted somatic stem cells (USSCs) is described. This rare population grows adherently and can be expanded to 1015 cells without losing pluripotency. In vitro USSCs showed homogeneous differentiation into osteoblasts, chondroblasts, adipocytes, and hematopoietic and neural cells including astrocytes and neurons that express neurofilament, sodium channel protein, and various neurotransmitter phenotypes. Stereotactic implantation of USSCs into intact adult rat brain revealed that human Tau-positive cells persisted for up to 3 mo and showed migratory activity and a typical neuron-like morphology. In vivo differentiation of USSCs along mesodermal and endodermal pathways was demonstrated in animal models. Bony reconstitution was observed after transplantation of USSC-loaded calcium phosphate cylinders in nude rat femurs. Chondrogenesis occurred after transplanting cell-loaded gelfoam sponges into nude mice. Transplantation of USSCs in a noninjury model, the preimmune fetal sheep, resulted in up to 5% human hematopoietic engraftment. More than 20% albumin-producing human parenchymal hepatic cells with absence of cell fusion and substantial numbers of human cardiomyocytes in both atria and ventricles of the sheep heart were detected many months after USSC transplantation. No tumor formation was observed in any of these animals.
30
Gáll, Zsolt, Krisztina Kelemen, István Mihály, Pál Salamon, Ildikó Miklóssy, Brigitta Zsigmond e Melinda Kolcsár. "Role of Lacosamide in Preventing Pentylenetetrazole Kindling-Induced Alterations in the Expression of the Gamma-2 Subunit of the GABAA Receptor in Rats". Current Molecular Pharmacology 13, n. 3 (9 luglio 2020): 251–60. http://dx.doi.org/10.2174/1874467213666200102095023.
Testo completoAbstract (sommario):
Background: Epilepsy remains challenging to treat still no etiologic treatment has been identified, however, some antiepileptic drugs (AEDs) are able to modify the pathogenesis of the disease. Lacosamide (LCM) has been shown to possess complex anticonvulsant and neuroprotective actions, being an enhancer of the slow inactivation of voltage-gated sodium channels, and it has the potential to prevent epileptogenesis. Recent evidence has shown that LCM indirectly improves the function of GABAA receptors. Receptors at most GABAergic synapses involve the gamma-2 subunit, which contributes to both phasic and tonic inhibition, and its presence assures benzodiazepine sensitivity. Moreover, mutant gamma-2 subunits were associated with generalized epilepsy syndromes. In animal models, the expression of the gamma-2 subunit of the gamma-aminobutyric acid A receptor (GABAAg2) was shown to be increased in pentylenetetrazole (PTZ)-induced chemical kindling in Wistar rats. Objective: This study hypothesized that LCM might affect the kindling process by influencing the expression of GABAA receptors in the hippocampus. Methods: The gene and protein expression levels of the GABAAg2 were studied using RT-qPCR and immunofluorescent staining. Results: It was found that LCM treatment (10 mg/kg i.p. daily for 57 days) reduced the maximal intensity of the PTZ-induced seizures but did not prevent kindling. On the other hand, LCM treatment reverted the increase of mRNA expression of GABAAg2 in the hippocampus and prevented the decrease of GABAAg2 protein in the hippocampal CA1 region. Conclusion: LCM could exhibit modulatory effects on the GABAergic system of the hippocampus that may be independent of the anticonvulsant action.
31
Kaufmann, Dan, Emily A. Bates, Boris Yagen, Meir Bialer, Gerald H. Saunders, Karen Wilcox, H. Steve White e KC Brennan. "sec-Butylpropylacetamide (SPD) has antimigraine properties". Cephalalgia 36, n. 10 (19 luglio 2016): 924–35. http://dx.doi.org/10.1177/0333102415612773.
Testo completoAbstract (sommario):
Background Though migraine is disabling and affects 12%–15% of the population, there are few drugs that have been developed specifically for migraine prevention. Valproic acid (VPA) is a broad-spectrum antiepileptic drug (AED) that is also used for migraine prophylaxis, but its clinical use is limited by its side effect profile. sec-Butylpropylacetamide (SPD) is a novel VPA derivative, designed to be more potent and tolerable than VPA, that has shown efficacy in animal seizure and pain models. Methods We evaluated SPD’s antimigraine potential in the cortical spreading depression (CSD) and nitroglycerin (NTG) models of migraine. To evaluate SPD’s mechanism of action, we performed whole-cell recordings on cultured cortical neurons and neuroblastoma cells. Results In the CSD model, the SPD-treated group showed a significantly lower median number of CSDs compared to controls. In the NTG-induced mechanical allodynia model, SPD dose-dependently reduced mechanical sensitivity compared to controls. SPD showed both a significant potentiation of GABA-mediated currents and a smaller but significant decrease in NMDA currents in cultured cortical neurons. Kainic acid-evoked currents and voltage-dependent sodium channel currents were not changed by SPD. Conclusions These results demonstrate SPD’s potential as a promising novel antimigraine compound, and suggest a GABAergic mechanism of action.
32
Krylova, Irina B., Albina F. Safonova e Natalia R. Evdokimova. "Correction of hypoxic state by metabolic precursors of endogenous activator of mitochondrial ATP-dependent K+channels". Reviews on Clinical Pharmacology and Drug Therapy 16, n. 3 (15 dicembre 2018): 25–31. http://dx.doi.org/10.17816/rcf16325-31.
Testo completoAbstract (sommario):
Aim. The antihypoxic properties of uridine and uridine-5'-monophosphate (UMP), which are the metabolic precursors of the natural activator of mitochondrial ATP-dependent K+ channels (mitoKATP channels) uridine diphosphat were investigated on the models of hypoxic hypoxia with hypercapnia (HHH), hemic hypoxia and local circulatory hypoxia.
Methods. HHH was created in males and females white mice weighing 28-30 g. The animals were placed one by one in hermetically closed container and the duration of their life was determined. The antihypoxic activity of the substances was compared with the reference anthypoxant amtizole (50 mg/kg). Hemic hypoxia was caused in Wistar rats weighing 350-370 g by the injection of sodium nitrite (intramuscularly, 100 mg/kg). Uridine or UMP 30 mg/kg was injected intraperitoneally 30 minutes before the onset of HHH and hemic hypoxia. Local circulatory hypoxia was modeled in male Wistar rats weighing 250-300 g. Acute coronary occlusion lasting 60 min was reproduced by legation of descending branch of the left coronary artery (LCA). Uridine or UMP (30 mg/kg) was administered intravenously 5 minutes prior to LCA occlusion. Selective blocker of mitoKATP channels 5-hydroxydecanoate (5 mg/kg, intravenously, 5 minutes prior uridine or UMP) was used to determine the role of these channels in the mechanism of antihypoxic action of the studied drugs. The volume of the damaged myocardium was used as the marker of antihypoxic activity of uridine and UMP.
Results. Different resistance to hypoxia in female and male mice was observed in HHH. The female mice were more resistant, their life duration was 43% more than the males. Uridine and UMP displayed antihypoxic activity only in male mice, increasing their life duration by 25% and 20% respectively. This effect was 2 times less than that of amtisol. In similar conditions in females mice the preparations did not show a protective effect. In hemic hypoxia the life duration of rats treated with uridine and UMP did not differ from the control values. Circulatory hypoxia, caused by occlusion of the LCA, led to the formation of a local zone of myocardial damage. Uridine or UMP decreased the damage zone in 2 and 3,5 times respectively. The inhibitor of mitoKATP channels blocked the protective effect of these compounds.
Conclusion. Uridine and UMP have a distinct antihypoxic effect in HHH and a marked protective effect in local circulatory hypoxia. The antihypoxic activity of druges in HHH is manifested differently in female and male mice. It may be due to sexual differences in the resistance to hypoxia. The maximum effect is observed in male who have initially low resistance to oxygen deficiency. The mechanism of the protective action of uridine and UMP in the circulatory hypoxia is associated with the activation of mitoKATP channels.
33
Downs, Charles A., David Trac, Elizabeth M. Brewer, Lou Ann Brown e My N. Helms. "Chronic Alcohol Ingestion Changes the Landscape of the Alveolar Epithelium". BioMed Research International 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/470217.
Testo completoAbstract (sommario):
Similar to effects of alcohol on the heart, liver, and brain, the effects of ethanol (EtOH) on lung injury are preventable. Unlike other vital organ systems, however, the lethal effects of alcohol on the lung are underappreciated, perhaps because there are no signs of overt pulmonary disorder until a secondary insult, such as a bacterial infection or injury, occurs in the lung. This paper provides overview of the complex changes in the alveolar environment known to occur following both chronic and acute alcohol exposures. Contemporary animal and cell culture models for alcohol-induced lung dysfunction are discussed, with emphasis on the effect of alcohol on transepithelial transport processes, namely, epithelial sodium channel activity (ENaC). The cascading effect of tissue and phagocytic Nadph oxidase (Nox) may be triggered by ethanol exposure, and as such, alcohol ingestion and exposure lead to a prooxidative environment; thus impacting alveolar macrophage (AM) function and oxidative stress. A better understanding of how alcohol changes the landscape of the alveolar epithelium can lead to improvements in treating acute respiratory distress syndrome (ARDS) for which hospitalized alcoholics are at an increased risk.
34
Jurj, Ancuta, Ciprian Tomuleasa, Tiberiu T. Tat, Ioana Berindan Neagoe, Stefan V. Vesa e Daniela C. Ionescu. "Antiproliferative and Apoptotic Effects of Lidocaine on Human Hepatocarcinoma Cells. A preliminary study". Journal of Gastrointestinal and Liver Diseases 26, n. 1 (1 marzo 2017): 45–50. http://dx.doi.org/10.15403/jgld.2014.1121.261.juj.
Testo completoAbstract (sommario):
Background & Aims: It is now well documented that certain anesthetic techniques may influence long term outcome in cancer patients undergoing surgery. More recently, local anesthetics proved certain antiproliferative effects in cancer cells. In our study, we aimed to investigate if lidocaine has antiproliferative effects in human hepatocarcinoma cells and to identify possible mechanisms of these effects.Methods. We investigated the inhibitory effect of different concentrations of lidocaine on the proliferation of cultured HepG2 human hepatocarcinoma cells and LX2 normal liver fibroblasts. Cells were exposed to nine different concentrations of lidocaine for 72h. MTT assay was used to investigate HepG2 and LX2 proliferation while Western blotting was used for detection of p53 expression level.Results. Our data showed that lidocaine inhibited cell proliferation in a concentration-dependent manner in both HepG2 and LX2. The antiproliferative effects of lidocaine in LX2 were significantly diminished as compared with those in HepG2 (p< 0.001). Similarly, the expression level of p53 was significant decreased in HepG2 lines treated with lidocaine as compared with control and LX2 (p = 0.0241).Conclusions. In clinically relevant concentrations, lidocaine had significant antiproliferative effects on human hepatocarcinoma cells. These effects were time and dose-dependent. One of the possible mechanisms of these effects is by modifying the P53 expression level. The relevance of these findings in clinical practice is limited; clinical impact of these effects on the outcome of patients with hepatocarcinoma undergoing surgery or minimal invasive procedures needs to be demonstrated in future animal models and clinical studies.Abbreviations: DMSO: dimethyl sulfoxide; DNA: deoxyribonucleic acid; EDTA: ethylenediaminetetraacetic acid; EGFR: epidermal growth factor receptor; MTT assay: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay; NK cells: natural killer cells; RCTs: randomized controlled studies; VGSC: voltage gated sodium channels.
35
Keita, Hawa, Claire Lepouse, Danielle Henzel, Jean-Marie Desmonts e Jean Mantz. "Riluzole Blocks Dopamine Release Evoked by N-methyl-D-aspartate, Kainate, and Veratridine in the Rat Striatum". Anesthesiology 87, n. 5 (1 novembre 1997): 1164–71. http://dx.doi.org/10.1097/00000542-199711000-00021.
Testo completoAbstract (sommario):
Background Dopamine (DA) is released in large amounts during cerebral ischemia and may exacerbate tissue damage. Riluzole (54274 RP) is a recently developed agent that depresses glutamate neurotransmission in the central nervous system (CNS) and that may protect against ischemic injury in some animal models. Because glutamate stimulates the release of DA in the striatum, the authors hypothesized that riluzole could antagonize DA release in this structure. Methods Assay for DA release consisted of superfusing 3H-DA preloaded synaptosomes with artificial cerebrospinal fluid (1 ml/min, 37 degrees C) and measuring the radioactivity obtained from 1-min fractions over 22 min, first in the absence of any treatment (spontaneous release, 8 min), then in the presence of depolarizing agents combined with riluzole (0.1-100 microM, 5 min), and finally with no pharmacologic stimulation (9 min). The following depolarizing agents were tested: KCl (9, 15 mM), veratridine (0.01-1 microM), N-methyl-D-aspartate (NMDA, 0.1-1 mM), kainate (0.1-1 mM), and nicotine (0.01-0.5 mM). Assay for DA uptake was performed by measuring the radioactivity incorporated in synaptosomes incubated with 3H-DA (44 nM; 5 min; 37 degrees C). Results All depolarizing agents produced a significant, concentration-related increase from basal 3H-DA release. Riluzole was found to decrease the release induced by veratridine (1 microM), NMDA (1 mM), and kainate (1 mM) in a significant, concentration-related manner (IC50 = 9.5 microM, 1.6 microM, and 5.8 microM for veratridine, NMDA, and kainate, respectively). In contrast, it did not affect the release elicited by either KCl or nicotine. Riluzole had no significant effect on the specific 3H-DA uptake. Conclusions Riluzole produced a potent blockade of the release of DA mediated by activation of presynaptic sodium channels, NMDA, and kainate receptors. Depression of glutamate transmission together with blockade of DA release may contribute to the actions of this agent in vivo.
36
Wang, Qing, Sophie Clement, Giulio Gabbiani, Jean-Daniel Horisberger, Michel Burnier, Bernard C. Rossier e Edith Hummler. "Chronic hyperaldosteronism in a transgenic mouse model fails to induce cardiac remodeling and fibrosis under a normal-salt diet". American Journal of Physiology-Renal Physiology 286, n. 6 (giugno 2004): F1178—F1184. http://dx.doi.org/10.1152/ajprenal.00386.2003.
Testo completoAbstract (sommario):
Primary aldosteronism causes severe hypertension in humans (Conn's syndrome) with cardiac hypertrophy, characterized by a fibrosis more severe than the one observed in patients with essential hypertension. This suggests that aldosterone by itself may have specific and direct effects on cardiac remodeling through the activation of the cardiac mineralocorticoid receptor. Experimental evidence obtained in studying uninephrectomized rats treated with aldosterone or deoxycorticosterone (DOC) together with salt loading has led to similar conclusions. To examine the direct consequences of chronically elevated aldosterone levels on cardiac pathophysiology, we analyzed a mouse model (α-epithelial Na channel −/−Tg) that is normotensive under normal-salt diet but exhibits chronic hyperaldosteronism. Sixteen-month-old transgenic rescue mice that were kept under a regular salt diet that contains a small amount of sodium (0.3% Na+) displayed a compensated PHA-1 phenotype with normal body weight, normal kidney index, normal blood pressure, but 6.3-fold elevated plasma aldosterone levels compared with the age-matched control group. Peripheral resistance of distal colon to aldosterone was shown by a significant decrease of the amiloride-sensitive rectal potential difference, and its diurnal cyclicity was blunted. Despite chronically high plasma aldosterone levels, these animals do not show any evidence of cardiac hypertrophy, remodeling, or fibrosis, using collagen staining and anti-α-skeletal and α-smooth actin immunochemical labeling of heart sections. Cardiac fibrosis as seen in DOC- or aldosterone/salt-treated animal models is therefore likely to be due to the synergistic effect of salt, aldosterone, and other confounding factors rather than to the elevated circulating aldosterone levels alone.
37
Lemme, Marta, Ingke Braren, Maksymilian Prondzynski, Bülent Aksehirlioglu, Bärbel M. Ulmer, Mirja L. Schulze, Djemail Ismaili et al. "Chronic intermittent tachypacing by an optogenetic approach induces arrhythmia vulnerability in human engineered heart tissue". Cardiovascular Research 116, n. 8 (9 ottobre 2019): 1487–99. http://dx.doi.org/10.1093/cvr/cvz245.
Testo completoAbstract (sommario):
Abstract Aims Chronic tachypacing is commonly used in animals to induce cardiac dysfunction and to study mechanisms of heart failure and arrhythmogenesis. Human induced pluripotent stem cells (hiPSC) may replace animal models to overcome species differences and ethical problems. Here, 3D engineered heart tissue (EHT) was used to investigate the effect of chronic tachypacing on hiPSC-cardiomyocytes (hiPSC-CMs). Methods and results To avoid cell toxicity by electrical pacing, we developed an optogenetic approach. EHTs were transduced with lentivirus expressing channelrhodopsin-2 (H134R) and stimulated by 15 s bursts of blue light pulses (0.3 mW/mm2, 30 ms, 3 Hz) separated by 15 s without pacing for 3 weeks. Chronic optical tachypacing did not affect contractile peak force, but induced faster contraction kinetics, shorter action potentials, and shorter effective refractory periods. This electrical remodelling increased vulnerability to tachycardia episodes upon electrical burst pacing. Lower calsequestrin 2 protein levels, faster diastolic depolarization (DD) and efficacy of JTV-519 (46% at 1 µmol/L) to terminate tachycardia indicate alterations of Ca2+ handling being part of the underlying mechanism. However, other antiarrhythmic compounds like flecainide (69% at 1 µmol/L) and E-4031 (100% at 1 µmol/L) were also effective, but not ivabradine (1 µmol/L) or SEA0400 (10 µmol/L). Conclusion We demonstrated a high vulnerability to tachycardia of optically tachypaced hiPSC-CMs in EHT and the effective termination by ryanodine receptor stabilization, sodium or hERG potassium channel inhibition. This new model might serve as a preclinical tool to test antiarrhythmic drugs increasing the insight in treating ventricular tachycardia.
38
Butler, Stephen. "Buprenorphine—Clinically useful but often misunderstood". Scandinavian Journal of Pain 4, n. 3 (1 luglio 2013): 148–52. http://dx.doi.org/10.1016/j.sjpain.2013.05.004.
Testo completoAbstract (sommario):
AbstractBackgroundThere are a number of false myths about buprenorphine based on unconfirmed animal data, even from isolated animal organs, and early clinical research. These myths came into textbooks on pharmacology and pain about 30 years ago and have been difficult to eradicate. Animal models of pain and pain relief are notoriously unreliable as predictors of human clinical effects. The fact is that in clinical practice there is NO bell-shaped dose-response curve, there is NO plateau on the dose-response curve, and there is NO antagonist effect from buprenorphine on other mu-opioid agonists.MethodsThis narrative, topical review of relevant research publications evaluates new knowledge on the pharmacodynamics and pharmacokinetics of buprenorphine of importance in clinical practice.ResultsBuprenorphine is a potent opioid analgesic acting on all four opioid receptors: it is an agonist on the mu-, the delta, and the ORL-1 receptors. It is an antagonist at the kappa-receptor. Buprenorphine has a number of active metabolites with different effects on the four opioid receptors; all except the norbup-3-glu are analgesic. Buprenorphine itself is not a respiratory depressant or sedative, but some of its active metabolites are. Buprenorphine and its active metabolites are not excreted by the kidney. Therefore buprenorphine may be used in patients with advanced renal failure.Buprenorphine has a slow onset and a long offset. These properties are advantageous, except sometimes when treating severe acute pain. Its agonist effect on the ORL-1 receptor reduces reward-effects and slows the development of tolerance to the analgesic effects.Buprenorphine inhibits voltage-gated sodium-channels and enhances and prolongs peripheral nerve blocks. Its ORL-1 -effect at the spinal cord may do the same.Buprenorphine is well suited for treatment of chronic pain, especially chronic neuropathic pain and cancer pain. The beneficial effects as a co-medication during treatment of the opioid-abuse disease are due to its slow onset (less “kick-effect”). Its prolonged offset-time reduces the likelihood of acute withdrawal problems and reduces the “craving” of opioids.Adverse effectsBuprenorphine, being a mu-agonist, may induce or maintain opioid addiction. Illegally obtained high-dose transmucosal buprenorphine, intended for treatment of addiction, is dissolved and injected by opioid abusers. This is an increasing problem in some countries.ConclusionsBuprenorphine’s unusual pharmacodynamics and pharmacokinetics make it an ideal opioid for treatment of most chronic pain conditions where opioid therapy is indicated.ImplicationsBuprenorphine is a well studied and often misunderstood analgesic opioid drug. The evidence base predicts that it will be an increasingly important alternative for treatment of chronic pain conditions caused by cancer and non-cancer diseases. It will continue to be an attractive alternative to methadone for opioid abuse rehabilitation.
39
Zennaro, Maria-Christina, Amanda Jane Rickard e Sheerazed Boulkroun. "Genetics in endocrinology: Genetics of mineralocorticoid excess: an update for clinicians". European Journal of Endocrinology 169, n. 1 (luglio 2013): R15—R25. http://dx.doi.org/10.1530/eje-12-0813.
Testo completoAbstract (sommario):
Aldosterone plays a major role in the regulation of sodium and potassium homeostasis and blood pressure. More recently, aldosterone has emerged as a key hormone mediating end organ damage. In extreme cases, dysregulated aldosterone production leads to primary aldosteronism (PA), the most common form of secondary hypertension. However, even within the physiological range, high levels of aldosterone are associated with an increased risk of developing hypertension over time. PA represents the most common and curable form of hypertension, with a prevalence that increases with the severity of hypertension. Although genetic causes underlying glucocorticoid-remediable aldosteronism, one of the three Mendelian forms of PA, were established some time ago, somatic and inherited mutations in the potassium channel GIRK4 have only recently been implicated in the formation of aldosterone-producing adenoma (APA) and in familial hyperaldosteronism type 3. Moreover, recent findings have shown somatic mutations in two additional genes, involved in maintaining intracellular ionic homeostasis and cell membrane potential, in a subset of APAs.This review summarizes our current knowledge on the genetic determinants that contribute to variations in plasma aldosterone and renin levels in the general population and the genetics of familial and sporadic PA. Various animal models that have significantly improved our understanding of the pathophysiology of excess aldosterone production are also discussed. Finally, we outline the cardiovascular, renal, and metabolic consequences of mineralocorticoid excess beyond blood pressure regulation.
40
Billen, Bert, Frank Bosmans e Jan Tytgat. "Animal Peptides Targeting Voltage-Activated Sodium Channels". Current Pharmaceutical Design 14, n. 24 (1 agosto 2008): 2492–502. http://dx.doi.org/10.2174/138161208785777423.
Testo completo
41
Ozawa, T., Y. Nagakura, Y. Ohkura, S. Kakimoto, H. Suzaka, T. Kiso, T. Watabiki et al. "F639 A NOVEL STATE-DEPENDENT SODIUM CHANNEL INHIBITOR 3-METHOXY-N-{2-[4-(2-PHENYLETHYL)PIPERIDIN-1-YL]ETHYL}- PYRIDINE-4-CARBOXAMIDE (AS1512706-00) EXERTS ANALGESIC EFFECTS IN A BROAD RANGE OF CHRONIC PAIN ANIMAL MODELS". European Journal of Pain Supplements 5, S1 (settembre 2011): 180. http://dx.doi.org/10.1016/s1754-3207(11)70619-8.
Testo completo
42
Liebeskind, Benjamin J., David M. Hillis e Harold H. Zakon. "Independent acquisition of sodium selectivity in bacterial and animal sodium channels". Current Biology 23, n. 21 (novembre 2013): R948—R949. http://dx.doi.org/10.1016/j.cub.2013.09.025.
Testo completo
43
Deuchar, Graeme A., Danielle McLean, Patrick W. F. Hadoke, David G. Brownstein, David J. Webb, John J. Mullins, Karen Chapman, Jonathan R. Seckl e Yuri V. Kotelevtsev. "11β-Hydroxysteroid Dehydrogenase Type 2 Deficiency Accelerates Atherogenesis and Causes Proinflammatory Changes in the Endothelium in Apoe−/− Mice". Endocrinology 152, n. 1 (1 gennaio 2011): 236–46. http://dx.doi.org/10.1210/en.2010-0925.
Testo completoAbstract (sommario):
Abstract Mineralocorticoid receptor (MR) activation is proinflammatory and proatherogenic. Antagonism of MR improves survival in humans with congestive heart failure caused by atherosclerotic disease. In animal models, activation of MR exacerbates atherosclerosis. The enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) prevents inappropriate activation of the MR by inactivating glucocorticoids in mineralocorticoid-target tissues. To determine whether glucocorticoid-mediated activation of MR increases atheromatous plaque formation, we generated Apoe−/−/11β-HSD2−/− double-knockout (E/b2) mice. On chow diet, E/b2 mice developed atherosclerotic lesions by 3 months of age, whereas Apolipoprotein E (Apoe−/−) mice remained lesion free. Brachiocephalic plaques in 3-month-old E/b2 mice showed increased macrophage and lipid content and reduced collagen content compared with similar sized brachiocephalic plaques in 6-month-old Apoe−/− mice. Crucially, treatment of E/b2 mice with eplerenone, an MR antagonist, reduced plaque development and macrophage infiltration while increasing collagen and smooth muscle cell content without any effect on systolic blood pressure. In contrast, reduction of systolic blood pressure in E/b2 mice using the epithelial sodium channel blocker amiloride produced a less-profound atheroprotective effect. Vascular cell adhesion molecule 1 expression was increased in the endothelium of E/b2 mice compared with Apoe−/− mice. Similarly, aldosterone increased vascular cell adhesion molecule 1 expression in mouse aortic endothelial cells, an effect mimicked by corticosterone only in the presence of an 11β-HSD2 inhibitor. Thus, loss of 11β-HSD2 leads to striking atherogenesis associated with activation of MR, stimulating proinflammatory processes in the endothelium of E/b2 mice.
44
Bosmans, Frank, Mirela Milescu e Kenton J. Swartz. "Palmitoylation Affects the Interaction of Animal Toxins with Sodium Channels". Biophysical Journal 100, n. 3 (febbraio 2011): 422a. http://dx.doi.org/10.1016/j.bpj.2010.12.2497.
Testo completo
45
Liebeskind, Benjamin J., David M. Hillis e Harold H. Zakon. "Phylogeny Unites Animal Sodium Leak Channels with Fungal Calcium Channels in an Ancient, Voltage-Insensitive Clade". Molecular Biology and Evolution 29, n. 12 (19 luglio 2012): 3613–16. http://dx.doi.org/10.1093/molbev/mss182.
Testo completo
46
Bagnéris, Claire, Claire E. Naylor, Emily C. McCusker e B. A. Wallace. "Structural model of the open–closed–inactivated cycle of prokaryotic voltage-gated sodium channels". Journal of General Physiology 145, n. 1 (15 dicembre 2014): 5–16. http://dx.doi.org/10.1085/jgp.201411242.
Testo completoAbstract (sommario):
In excitable cells, the initiation of the action potential results from the opening of voltage-gated sodium channels. These channels undergo a series of conformational changes between open, closed, and inactivated states. Many models have been proposed for the structural transitions that result in these different functional states. Here, we compare the crystal structures of prokaryotic sodium channels captured in the different conformational forms and use them as the basis for examining molecular models for the activation, slow inactivation, and recovery processes. We compare structural similarities and differences in the pore domains, specifically in the transmembrane helices, the constrictions within the pore cavity, the activation gate at the cytoplasmic end of the last transmembrane helix, the C-terminal domain, and the selectivity filter. We discuss the observed differences in the context of previous models for opening, closing, and inactivation, and present a new structure-based model for the functional transitions. Our proposed prokaryotic channel activation mechanism is then compared with the activation transition in eukaryotic sodium channels.
47
Rehberg, Benno, Yong-Hong Xiao e Daniel S. Duch. "Central Nervous System Sodium Channels Are Significantly Suppressed at Clinical Concentrations of Volatile Anesthetics". Anesthesiology 84, n. 5 (1 maggio 1996): 1223–33. http://dx.doi.org/10.1097/00000542-199605000-00025.
Testo completoAbstract (sommario):
Background Although voltage-dependent sodium channels have been proposed as possible molecular sites of anesthetic action, they generally are considered too insensitive to be likely molecular targets. However, most previous molecular studies have used peripheral sodium channels as models. To examine the interactions of volatile anesthetics with mammalian central nervous system voltage-gated sodium channels, rat brain IIA sodium channels were expressed in a stably transfected Chinese hamster ovary cell line, and their modification by volatile anesthetics was examined. Methods Sodium currents were measured using whole cell patch clamp recordings. Test solutions were equilibrated with the test anesthetics and perfused externally on the cells. Anesthetic concentrations in the perfusion solution were determined by gas chromatography. Results All anesthetics significantly suppressed sodium currents at clinical concentrations. This suppression occurred through at least two mechanisms: (1) a potential-independent suppression of resting or open sodium channels, and (2) a hyperpolarizing shift in the voltage-dependence of channel inactivation resulting in a potential-dependent suppression of sodium currents. The voltage-dependent interaction results in IC50 values for anesthetic suppression of sodium channels that are close to clinical concentrations at potentials near the resting membrane potential.
48
Smith, Natalie E., e Ben Corry. "Mutant bacterial sodium channels as models for local anesthetic block of eukaryotic proteins". Channels 10, n. 3 (18 marzo 2016): 225–37. http://dx.doi.org/10.1080/19336950.2016.1148224.
Testo completo
49
URBAN, BERND W., CHRISTIAN FRENKEL, DANIEL S. DUCH e AUDREY B. KAUFF. "Molecular Models of Anesthetic Action on Sodium Channels, Including Those from Human Brain". Annals of the New York Academy of Sciences 625, n. 1 Molecular and (giugno 1991): 327–43. http://dx.doi.org/10.1111/j.1749-6632.1991.tb33861.x.
Testo completo
50
Otsuki, Makoto, Mitsuyoshi Yamamoto e Taizo Yamaguchi. "Animal Models of Chronic Pancreatitis". Gastroenterology Research and Practice 2010 (2010): 1–8. http://dx.doi.org/10.1155/2010/403295.
Testo completoAbstract (sommario):
Animal models for CP in rats can be classified into 2 groups: one is noninvasive or nonsurgical models and the other is invasive or surgical models. Pancreatic injury induced by repetitive injections of supramaximal stimulatory dose of caerulein (Cn) or by intraductal infusion of sodium taurocholate (NaTc) recovered within 14 days, whereas that caused by repetitive injection of arginine or by intraductal infusion of oleic acid was persistent. However, the destroyed acinar tissues were replaced by fatty tissues without fibrosis. Transient stasis of pancreatic fluid flow by 0.01% agarose and minimum injury of the pancreatic duct by 0.1% NaTc solution induced progressive pancreatic injury although one alone is insufficient to cause persistent pancreatic injury. However, the damaged tissue was replaced by fatty tissue without fibrosis. Continuous pancreatic ductal hypertension (PDH) caused diffuse interlobular and intralobular fibrosis closely resembling human CP.