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1
Wang, Xiaoliang. "a1 Na/K-ATPase Integrator Function in Animal Physiology". University of Toledo Health Science Campus / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=mco1501068137400808.
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Lomas, Caroline Anne. "The effect of supplementary light on the behaviour, physiology and productivity of cattle". Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239841.
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Sharif, Naeini Reza. "Contribution of the Trpv1 gene to the physiology of supraoptic neurons". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111867.
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The release of vasopressin (VP) from magnocellular neurosecretory cells (MNCs) of the supraoptic (SON) and paraventricular (PVN) nuclei is essential to hydromineral homeostasis. This release is controlled by several physiological stimuli, including changes in the osmotic pressure of the extracellular fluid, and in core body temperature. The osmotic control of VP release is mediated by specific and highly sensitive 'osmoreceptors'. Indeed, VP-releasing neurons in the SON are directly osmosensitive, and this osmosensitivity is mediated by stretch-inhibited cation channels. The molecular identity of these channels, however, remains unknown. The thermal control of VP release, on the other hand, is largely unexplained. In this thesis, we demonstrate that the mouse SON is a valid model for investigating the molecular basis of osmotransduction. We show that hyperosmotically-induced increases in membrane conductance are blocked by ruthenium red (RR), a non selective blocker of TRPV channels. In addition, SON neurons were found to express an N-terminal splice variant of TRPV1, but not full-length TRPV1. Unlike their wild-type counterparts, SON neurons in Trpv1 knockout (Trpv1-/-) mice could not generate RR-sensitive increases in membrane conductance and depolarizing potentials in response to hyperosmotic stimulation. Moreover, Trpv1-/-mice showed a pronounced serum hyperosmolality under basal conditions and severely compromised VP responses to osmotic stimulation in vivo. These results suggest that the Trpv1 gene may encode a central component of the osmoreceptor. Furthermore, we demonstrate that VP neurons are intrinsically thermosensitive. In these neurons, thermal stimuli spanning core body temperatures activate a RR-sensitive non selective cation current. Interestingly, VP neurons isolated from Trpv1 -/-mice are significantly less thermosensitive. These results suggest that channels encoded by the Trpv1 gene can confer thermosensitivity in the physiological range. Overall, these data suggest that products of the Trpv1 gene in VP neurons may represent a molecular point of convergence for the detection of osmotic and thermal stimuli.
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Senko, Alexander W. (Alexander William). "Transgene-free strategies for wireless control of animal physiology using magnetite nanoparticles". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122538.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 130-141).
Bioelectronic medicines are emerging therapies designed to control human physiology using electrically actuated stimuli instead of drugs. The most famous example is deep brain stimulation (DBS) for Parkinson's disease, in which electrodes are used to control brain activity and prevent tremors. An idealized version of this therapy would use soft materials and be wireless in order to be minimally invasive and cause minimal damage to brain tissue. Magnetic fields are an appealing candidate for wireless therapies because at many frequencies and amplitudes, the human body is similar enough in its magnetic response to vacuum that magnetic fields can penetrate arbitrarily deep. When combined with magnetic nanoparticles of biocompatible iron oxide, which can dissipate heat or produce forces when subjected to applied magnetic fields, magnetic fields can be applied from outside the body and evoke a physiological response within. This thesis describes the synthesis of large disc-shaped magnetic particles which undergo mechanical motion under lower frequency alternating magnetic fields. This mechanical motion enables a new paradigm of activating mechanosensitive ion channels, with increased scalability of the magnetic field apparatuses compared to the high-frequency fields needed to produce heat from magnetic nanoparticles. Wireless magnetic nanoparticle-mediated stimulation has often relied on transgenes, but by choosing tissues that endogenously express the proteins required to detect the physical stimuli (like heat or force) produced by the nanoparticles, it is possible to avoid the need for transgenes. Not relying on transgenes significantly lowers the barrier to clinical translation of this therapy platform.
by Alexander W. Senko.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
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Al-Jamal, Rehab. "The interaction between dynamic lung physiology, the extracellular matrix and mechanical strain /". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37861.
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Recently, various proteoglycans (PGs) have been identified in the lung. The first objective of this thesis was to test the hypothesis that matrix glycosaminoglycans contribute to lung tissue viscoelasticity. Lung parenchymal strips were exposed to specific glycosaminoglycans-degradating enzymes to determine whether the mechanical properties of the tissue were affected. The degradation of heparan sulphate and chondroitin/dermatan sulphate glycosaminoglycans caused significant increases in energy dissipation and dynamic resistance relative to control strips. Hyaluronidase treatment did not alter any of the dynamic or static measures. Since PGs were found to be part of the stress bearing structure, the second part of the thesis aimed at examining whether subjecting the lung to excessive mechanical force can cause alteration in PG composition so as to adapt to the altered stress bearing requirement. To address this hypothesis, the effect of different ventilation regimes on lung tissue mechanics and PGs was examined in an in vivo rat model. After 2 h of mechanical ventilation, lung tissue elastance and resistance were significantly increased in rats ventilated with tidal volume of 30 ml/kg at 0 positive end-expiratory pressure (Vt30PEEP0) as compared to controls (Vt8PEEP1.5). Versican, a basement membrane heparan sulphate PG and biglycan, were all increased in rat lungs ventilated with Vt30PEEP0 as compared to control. These data demonstrated that alterations in lung tissue mechanics with excessive mechanical ventilation are accompanied by changes in all classes of ECM PGs. However, whether the alteration seen in PG composition resulted from excessive mechanical ventilation directly was unclear. In addition the cellular source of these PGs was not determined. Therefore, the aim of the third part of the thesis was to investigate and characterize the effect of mechanical strain on lung fibroblast PG production in vitro. We found cell layer associated versican protein in
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Dableh, Liliane J. "Cannabinoid receptors in animal models of acute, tonic and chronic pain". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29428.
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The aim of the work presented here is to evaluate the effects of cannabinoids in three animal models of pain: acute, tonic and chronic. The tail flick test (acute pain) was used to test the effect of the cannabinoid agonist, WIN 55,212--2, on tail withdrawal latency from a noxious radiant heat source. It was also tested on the allodynia induced by either endogenous release or exogenous administration of substance P. WIN 55,212--2 was antinociceptive in this test, and blocked the substance P-induced allodynia, suggesting a post-synaptic site of action. The formalin test (tonic pain) was used to test the effects of the endogenous cannabinoid agonist, anandamide and the cannabinoid receptor antagonist AM 281. Anandamide was antinociceptive (with a short duration of action), and AM 281 was pronociceptive. When administered concomitantly, AM 281 blocked the effects of anandamide. When given alone and in the absence of a noxious stimulus, AM 281 was without effect. (Abstract shortened by UMI.)
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Sylvester, Christopher John. "A Demonstration of Photoresponsiveness in Laboratory Rats using Whole Animal and Neuroendocrine Approaches". W&M ScholarWorks, 1997. https://scholarworks.wm.edu/etd/1539626097.
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Téfit, Mélisandre. "Drosophila melanogaster and its bacterial partners : community dynamics and effects on animal physiology". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN055.
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Dans la nature, les relations symbiotiques sont très répandues, et d’une importance écologique fondamentale. Les animaux sont apparus, ont évolué et vivent maintenant constamment associés avec une multitude de micro-organismes. Parmi les différents types de symbioses existantes, celles liant le microbiote et son hôte occupent une place centrale et équilibrée, basée sur des relations commensales ou mutualistes entre les partenaires. Ce microbiote est de plus en plus étudié, notamment en raison du rôle crucial qu’il joue dans la santé animale ainsi que dans le développement de pathologies. Dans cette effort de recherche, Drosophila melanogaster représente un modèle de choix, grâce à la facilité de générer et maintenir des lignées de mouches axéniques, ainsi que de les réassocier avec une communauté microbienne définie.L’association de la drosophile avec l’un des ses commensaux naturels, Lactobacillus plantarum, a permis de révéler l’effet promoteur de croissance de cette bactérie. En cas de carence nutritionnelle, des larves associées avec L. plantarum se développent beaucoup plus rapidement que leurs semblables axéniques. L’ajustement du développement en fonction des conditions environnementales est cependant crucial pour la formation d’un individu à la santé optimale, et dans ce cas les individus grandissent plus vite alors que les conditions nutritionnelles sont pauvres. Nous avons donc cherché à déterminer si ce qui semble être un avantage au stade larvaire pouvait se révéler délétère pour les stades suivants et avoir un effet néfaste sur les mouches adultes. Nous avons montré que L. plantarum est bénéfique pour D. melanogaster tout au long du cycle de vie de la mouche et permet l’émergence précoce d’adultes matures et fertiles sans impact négatif sur leur santé et leurs performances. De plus, dans certaines conditions, cette souche commensale entraîne une augmentation de la durée de vie de mâles nutritionnellement carencés.Des études plus larges analysant l’interaction de la drosophile avec plusieurs espèces bactériennes peuvent informer sur la dynamique d’un microbiote de mouche. En effet, au sein de la niche environnementale, les bactéries sont échangées entre l’animal et son substrat nutritif, et ces transferts réciproques pourraient altérer la composition de la communauté. Nous avons étudié cette question en utilisant un microbiote naturel, et avons observé un haut degré de similitude entre les bactéries associées avec les mouches et la composition de la communauté bactérienne de la nourriture, illustrant le caractère stable de l’association du microbiote de la drosophile avec la population de mouches au sien de la niche.Ces résultats illustrent le pouvoir du modèle drosophile pour l’étude des interactions entre les animaux et leur microbiote, qui permet de déchiffrer la dynamique des communautés de bactéries commensales ainsi que leur impact sur la physiologie animaleIn nature, symbiotic relationships are widespread, and of paramount ecological importance. Animals have appeared, evolved, and are now living constantly associated with a variety of microorganisms. In the spectrum of different symbioses types, the microbiota occupies a central and balanced part by establishing commensalistic or mutualistic relationships with its host. Over the last years, the microbiota has been extensively studied given the crucial role it plays in animal health and disease. In this research effort, Drosophila melanogaster represents a fruitful model, thanks to the ease to generate and maintain axenic flies, and the simplicity of re-associating them with a defined microbial community.The association of Drosophila with one of its natural commensals, Lactobacillus plantarum, revealed a growth-promoting effect mediated by this bacterial species. In case of nutrient scarcity, larvae associated with L. plantarum develop twice faster than the germ-free ones. However, adjusting development to environmental cues is key to organismal fitness, and yet here animals are growing fast even though the nutritional conditions are poor. We thus questioned whether what seems like an advantage could in turn be deleterious at later stages, and adversely impact adult fitness. We showed that L. plantarum is a true beneficial partner for D. melanogaster throughout the fly life cycle. Indeed, it allows the precocious emergence of mature and fertile adults without fitness drawbacks, and in certain conditions, this commensal can even increase the lifespan of nutritionally challenged males.Broader studies assessing the interaction of Drosophila with several bacterial species can inform about the dynamics of a fly microbiota. Indeed, in the environmental niche bacteria are transferred between the fly and its nutritive substrate, and these reciprocal transfers could alter the composition of the community. We addressed this question using a wild-derived microbial community and observed a high degree of similarity between the bacteria associated with the flies and the composition of the community in the diet, illustrating the stable association of the Drosophila microbiota with the fly population in the niche.Altogether these results emphasize the power of the Drosophila model in the study of the relationships between animals and their microbiota, which allows deciphering the dynamics of commensal bacterial communities and their impact on animal physiology
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Mazzola, Carmen. "Neuropharmacology and Behaviural Animal Models". Thesis, Universita' degli Studi di Catania, 2011. http://hdl.handle.net/10761/93.
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Lo studio delle patologie umane richiede spesso l'ausilio di sperimentazioni animali. Generalmente i dati ottenuti in questi modelli permettono di ampliare le conoscenze sui meccanismi eziologici e sul trattamento delle patologie. Perche' un modello sperimentale sia considerato attendibile, deve avere specifici requisiti: face validity, construct validity and predictive validity. Rispettare tali criteri e' di enorme importanza per la ricerca in ambito fisiologico e farmacologico.The study of human disease often involves performing physiological and pharmacological experiments in animal models. Generally, experimental results obtained in these models are extrapolated to the human situation, providing new insights into disease mechanisms and treatment options. To be able to reliably extrapolate results obtained in animal experiments, it is important to consider the validity of the animal model used, i.e., the extent to which the model mimics the disease. This validity is often characterized by 1) the resemblance in symptoms (face validity), 2) shared etiology and underlying pathophysiological mechanisms (construct validity), and 3) similarity of pharmacological responses (predictive validity). Hence, the analysis of face, construct, and predictive validity of animal models constitutes a very important aspect in the study of disease physiology and pharmacology.
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Crouzet, Emmanuel. "Modèles animaux pour la recherche sur la cornée. Expérimentation animale et alternatives innovantes". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES066.
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La cornée est le hublot transparent de l’oeil. Bien que de nombreux modèles alternatifs utilisant des cornées animales ex vivo aient vu le jour durant ces 30 dernières années, les recherches préclinique (étude de nouvelles stratégies diagnostiques et thérapeutiques) et fondamentale sur la cornée ont toujours besoin de l’expérimentation animale in vivo. Elle fait aujourd’hui l’objet d’une réglementation stricte afin d’éviter tout abus et maltraitance. Les animaux les plus fréquemment utilisés en recherche cornéenne sont des mammifères (souris, rat, lapin, chat, chien, cochon, boeuf et primate non humain). Malgré leur proximité phylogénétique de l’Homme, ces animaux peuvent présenter des différences notables avec la cornée humaines qui doivent être connues pour ne pas induire de biais dans l’expérimentation. Les objectifs de cette thèse sont de mettre au point les modèles animaux et les méthodes alternatives nécessaires aux travaux du laboratoire BiiGC (EA 2521, Université de Saint-Étienne, France). Ils sont illustrés par 3 projets innovants : 1/une étude préclinique utilisant un modèle de kératoplastie transfixiante chez le lapin pour évaluer la prévention du rejet d’allogreffe de cornée par implant sous conjonctival de déxamethasone ; 2/Le développement d’un bioréacteur cornéen porcin pour l’analyse de la cicatrisation épithéliale ; 3/ l’utilisation d’un modèle lapin de lésion endothéliale pour l’étude de la régénération endothéliale. Ces 3 travaux innovant démontrent la diversité des modèles animaux nécessaires en recherche fondamentale et translationnelleThe cornea is the clear window of the eye. Although many alternative models using ex vivo animal corneas have emerged during the last 30 years, preclinical research (study of new diagnostic and therapeutic strategies) and fundamental corneal research still need animal experiments in vivo. The most commonly used animals in corneal research are mammals (mouse, rat, rabbit, cat, dog, pig, beef and non-human primate). Despite their phylogenetic proximity to humans, these animals may exhibit notable differences with the human cornea, which must be known so as not to induce bias into the experiment. The aims of this thesis are to develop the animal models and the alternative models necessary for the work of the BiiGC laboratory (EA2521, University of Saint-Etienne, France). They illustrated by 3 innovative projects: 1/ a preclinical study using penetrating keratoplasty model in rabbits to evaluate the prevention of corneal allografts rejection by a conjunctival implant of dexamethasone; 2/ The development of a porcine corneal bioreactor for the analysis of epithelial wound healing; 3/ The use of rabbit endothelial lesion model for the study of endothelial regeneration. These 3 innovative works demonstrate the diversity of animal models needed in fundamental and translational research
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Pickard, Julie Anne. "Nutritional influences on gut physiology and microflora in the post-weaned piglet". Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/12315/.
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In piglets, the post-weaning growth check is commonly associated with the weaning process that occurs within the European Union at approximately 3-4 weeks of age. The aims of the studies reported here were to investigate the contribution and importance of nutritional influences on the complex and multi-factorial problem of the post-weaning growth check in the piglet. Multi-disciplinary investigations focussed upon the relationship between post-weaning nutrition and the gut ecosystem with specific emphasis on gut physiology, immunity and microflora. The influence of dietary acid binding-capacity (ABC) on gut morphology characteristics was investigated in 20 newly-weaned piglets up to 14 days post-weaning. Piglets offered the low ABC diet displayed more rapid recovery of villus height (after a degree of villus atrophy) than control animals (P<0.001). Prior to the initial villus atrophy, villus height increased significantly throughout the experimental period for both dietary treatment groups (P<0.001; <0.001 (L); <0.001 (Q)). In control animals, villus width was greater (P=0.006) compared with treatment animals, and villus width increased over time for both groups (P<0.001; <0.001 (L); 0.014 (Q)). Crypt depth also increased temporally (P<0.001; <0.001 (L)) for both dietary groups, with treatment animals exhibiting the greatest overall dietary mean (P=0.009). No significant differences between ileal digesta pH and feed intake levels were determined. Despite the improvements in intestinal structure post-weaning, these effects were not manifested in increased performance, i.e. DLWG. The improvements in intestinal structure may not have been of significant magnitude to influence performance parameters. Dietary zinc oxide (ZnO) and avilamycin supplementation was found to exert a beneficial (although non-significant: P>0.05) effect on gut morphology; villus atrophy occurred over the initial 2 days post-weaning for animals fed ZnO, avilamycin or ZnO plus avilamycin (diets 2-4 respectively), compared to 4 days for control animals. No significant differences between intestinal coliform and lactobacilli load were established with respect to dietary treatment. Any differences observed in microflora load are most likely to be age-dependent. A positive relationship was established between dietary treatment (ZnO, avilamycin and ZnO plus avilamycin) on daily live weight gain post-weaning (P<0.001). Although not significant (P>0.05), a positive influence of dietary ZnO supplementation on feed intake levels was apparent, which may account, in part, for the enhanced growth performance. This finding was not however manifested through modifications of intestinal morphology or the lactobacilli and coliform populations studied. This further suggests that dietary ZnO may exert an effect either luminally or systemically. Further research is required to determine the mechanism responsible for the enhanced feed intake and DLWG response. The effects of feeding a yeast-based nucleotide source pre- and post-weaning revealed no significant differences with respect to villus height and width. Crypt depth was significantly greater in animals fed the treatment diet post-weaning (P<0.001). Post-weaning nucleotide-supplemented diets were found to significantly reduce intestinal coliform load (P=0.033). Such an effect was not evident in animals fed the diets pre-weaning, suggesting that the gut microflora may have adapted to the dietary regimen throughout the pre-weaning period. Lymphocyte blastogenesis assays revealed that piglets fed a yeast-based nucleotide source post-weaning might be immunosuppressed at the time weaning. Conversely, when the same diets (in terms of composition) were fed from 14 days pre-weaning (study 4), no indication of immunosuppression was evident. Since no dietary effects were apparent in either study, it is postulated that this could be a general effect of the diet per se and not the actual dietary composition. It is however also possible that the animals involved in study 4 were experiencing hypersensitivity reactions to the pre-weaning dietary antigens. These animals were also combating an E. coli infection. Additional studies are however required to identify conclusively a cause and effect relationship, and elucidate the complicated interactions between nutrition or feed intake and immunobiology in the post-weaned piglet. Implementation of dietary nucleotide-supplementation from 7 days pre-weaning through to 25 days post-weaning within a commercial environment was found to enhance significantly DLWG (P<0.001). In summary, the current work extends current knowledge and offers a greater understanding of the factors and complex process that influence the gut ecosystem and physiology in the post-weaned piglet. This thesis confirms the crucial role feed intake or, more specifically luminal nutrition, in post-weaned piglets and has highlighted key areas for future investigation.
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Monemdjou, Shadi. "Metabolic control and regulation of mitochondrial proton leak: Effects of UCP1 deficiency and aging in mice". Thesis, University of Ottawa (Canada), 1998. http://hdl.handle.net/10393/4293.
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The overall objective of this thesis was to examine various aspects of the metabolic significance and regulation of the mitochondrial proton leak. The research conducted specifically assesses the influence that leak has on age-associated changes in mitochondria, and the role that the leak plays in facultative energy expenditure of transgenic mice which lack uncoupling protein-1 (UCP1), a well known mediator of the proton leak. Proton leak in mitochondria has been studied for over ten years, but its exact mechanism has not yet been elucidated and only recently has it been realized that it might be mediated by uncoupling proteins (UCPs). UCPs may confer a mechanism for proton leakage and thus affect the efficiency of oxidative phosphorylation. Mice deficient in the gene for mitochondrial UCP1 (Ucp1-deficient mice) are cold-sensitive despite their abundant expression of genes for the isoforms (Ucp2 and Ucp3), and do not become more obese than controls when fed a high fat diet (Enerback et al. 1997) The objective of our work was to analyse the metabolic control and characteristics of proton leak in mitochondria from brown adipose tissue (BAT) of Ucp1-deficient mice and of heterozygote controls in order to establish the role of the UCPs in facultative thermogenesis. (Abstract shortened by UMI.)
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O'Connor, Timothy Michael. "Characterization of the PGE(2) receptor subtypes and the IP receptor in the rat medullary thick ascending limb". Thesis, University of Ottawa (Canada), 1997. http://hdl.handle.net/10393/4479.
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PGE$\sb2$ attenuates AVP-dependent solute transport in the medullary thick ascending limb of Henle (mTAL) and like the PGI$\sb2$ I-prostanoid (IP) receptor inhibits AVP-dependent water flow in the collecting duct. PGI$\sb2$ may play a role similar to PGE$\sb2$ in the mTAL. We therefore further characterize E-prostanoid (EP) receptor subtypes and the IP receptor in a freshly isolated suspension of rat mTAL. Using 10 nM PGE$\sb2,$ we confirmed previous work showing a Gi coupled EP$\sb3$ receptor subtype in rat mTAL that attenuates AVP-dependent cAMP by 70.7%. Pertussis toxin reversed this inhibitory response by 73.2%. In the absence of AVP, micromolar concentrations of PGE$\sb2$ and the EP$\sb2$ receptor subtype specific agonist butaprost produced significant elevations in cAMP levels, indicating the existence of the G$\rm\sb{s}$-coupled EP$\sb2$ receptor subtype. This response was insensitive to the EP$\sb4$ receptor subtype antagonist AH-23848B. Using the PGI$\sb2$ analogs iloprost (ILP) and cicaprost (CCP), we have demonstrated the presence of a Gi-coupled PGI$\sb2$ receptor. AVP-dependent cAMP was reduced 80% and 68.9% by 0.1uM ILP and 1 uM CCP respectively. Pertussis toxin reversed these inhibitory actions by 73%. Neither the EP$\sb3$ receptor subtype nor IP receptor inhibitory responses on AVP-dependent cAMP were sensitive to the EP$\sb1$ receptor subtype specific antagonist AH-6809 and the protein kinase C (PKC) inhibitors bisindolylmaleimide 1 and calphostin C. By associating in situ hybridization for receptor mRNA with TAL-specific Tamm-Horsfall glycoprotein immunostaining on serial sections from rat kidney, we have clearly shown EP$\sb3$ receptor subtype and IP receptor expression in the rat mTAL. These results suggest that a Gi-coupled IP receptor and the EP$\sb3$ receptor subtype play a role in attenuating the AVP-dependent cAMP in the rat mTAL.
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Vermette, Michel Gérard. "A role for epinephrine in acid-base and gas transfer regulation in rainbow trout". Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5112.
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Sigurdson, S. Lynn. "Control of brown adipose tissue growth and function in normal and myopathic hamsters". Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5567.
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Vandorpe, David H. "Distal tubule bicarbonate reabsorption". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5667.
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The purpose of this study was to elucidate certain aspects of the control of bicarbonate reabsorption in the surface distal tubule of rats made acidotic by ammonium chloride treatment. During acute metabolic acidosis, the effects of sodium delivery, water reabsorption, inhibition of carbonic anhydrase, and addition of the anion channel blocker SITS were determined. In addition, bicarbonate reabsorption was assessed during recovery from metabolic acidosis. Studies during the acute phase of acidosis: Sprague-Dawley rats were made acidotic by ammonium chloride gavage and then prepared for micropuncture. It was hypothesized that distal tubule bicarbonate transport might have components dependent on direct or indirect Na/H exchange, water reabsorption, carbonic anhydrase activity and chloride conductance. To test these hypotheses surface distal tubules were then microperfused in vivo at 8 nl/min with 4 different isoosmotic, bicarbonate containing solutions. These solutions were designed to (1) provide an index of the increased bicarbonate reabsorption evident in this model and assess the effect of the following on bicarbonate reabsorption: (2) sodium replacement with choline; (3) sodium substitution augmented by pharmacologic means (amiloride); (4) inhibition of carbonic anhydrase by acetazolamide. At 8 nl/min, collection of fluid from tubules perfused with all 4 solutions revealed significant bicarbonate reabsorption. Net distal tubule bicarbonate reabsorption was significantly increased in acidotic animals. Perfusion of tubules with sodium free solutions did not decrease this brisk reabsorptive flux, nor did perfusion of sodium free solutions which also contained amiloride. However, perfusion of tubules with the carbonic anhydrase inhibitor DIAMOX significantly decreased bicarbonate reabsorption. This is the first in vivo demonstration of such an effect in the distal tubule of the acidotic rat when bicarbonate load was held constant. The effect of sodium replacement at high perfusion rate was also studied, but again was not found to significantly alter bicarbonate reabsorption, although more bicarbonate was found to be reabsorbed at 25 nl/min than at 8 nl/min. Since some reports have suggested that a chloride conductance may play a role in acidification by proton pumps, the effects of perfusion with a chloride channel blocker was studied. Paired collections at 25 nl/min, with and without SITS, revealed a significant inhibitory effect of SITS. Studies during recovery from metabolic acidosis: Animals allowed to recover from the acidosis exhibited a rebound metabolic alkalosis. It was hypothesized that distal tubule bicarbonate reabsorption might contribute to this apparent overshoot of blood bicarbonate concentration. Tubules perfused 44 hours post gavage exhibited significant bicarbonate reabsorption at 8, 15, and 25 nl/min, despite the concurrent metabolic alkalosis. These are the first reported in vivo data of distal tubule bicarbonate reabsorption during rebound metabolic alkalosis. It is concluded that bicarbonate reabsorption in distal tubules of acidotic rats perfused in vivo at 8 nl/min was not affected by reduced sodium delivery, or water movement, but is partly dependent on carbonic anhydrase activity and may also be partly dependent on chloride permeability. In addition, bicarbonate reabsorption continues during the recovery phase, despite the existence of systemic metabolic alkalosis.
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Kinkead, Richard. "The role of circulating catecholamines in the regulation of breathing in teleosts". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5671.
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This thesis attempts to elucidate the role of epinephrine and/or norepinephrine in the regulation of ventilation in teleosts while also considering the effects of other potential ventilatory modulators. The ventilatory responses to various external respiratory challenges were quantified and compared with those in fish pre-treated with adrenoceptor antagonists. The effects of experimental elevation of circulating catecholamines on gill ventilation volume (Vw) were assessed. During hypoxia, pre-treatment of fish with either $\alpha$- or $\beta$-adrenoceptor antagonists did not affect the ventilatory response of rainbow trout (Oncorhyncus mykiss) or Atlantic cod (Gadus morhua), regardless of the degree of hypoxia used and the corresponding effects on circulating catecholamine levels. Furthermore, since increases in Vw were observed under mild hypoxia or hypercapnia it is concluded that elevation of circulating catecholamines is not a prerequisite for hyperventilatory responses to these stimuli. Pre-treatment of trout with a $\beta$-adrenoceptor antagonist (propranolol) prior to exposure to external hypercapnia prevented a sustained hyperventilation despite the absence of significantly elevated catecholamines in the circulation. This revealed that catecholamines of non-humoral origin are involved in the hyperventilatory response to hypercapnia. It is unlikely, at least in trout, that catecholamines play a stimulatory role in the regulation of ventilation. Respiratory acidosis may play a role in the control of ventilation in this species since external hypercapnia prevented the hypoventilatory response normally associated with hyperoxia. (Abstract shortened by UMI.)
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Vajsar, Jiri. "The mismatch negativity evoked by changes in the frequency of an auditory stimulus". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5679.
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This thesis deals with some of the unknown issues in slow auditory evoked potentials (AEPs). Slow AEPs were recorded in 10 healthy reading subjects. A change in the frequency of the tonebursts elicited an additional negativity--the mismatch negativity (MMN). The amplitude and latency of MMN changed with the magnitude of frequency deviance between stimuli which was varied between 50 and 2000 Hz. The voltage distributions of the MMN and N1 were significantly different from that of the SP. The MMN and N1 had their maximal amplitudes in the fronto-central areas, whereas the maximal amplitude of the SP was recorded frontally. The topographic mapping and statistical analysis of voltage distribution of individual waves enabled us to recognize and differentiate between the possible generators of the MMN, N1 and SP. Both the MMN and N1 are generated in the auditory cortices. The SP is more complexed and may consist of more than one component. (Abstract shortened by UMI.)
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Park, Ian R. A. "Studies of the growth and regulation of brown adipose tissue". Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5700.
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Giroux, Benoit. "Net shoulder joint moment and muscular activity during light weight handling at different heights and frequencies". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5728.
Texto completoResumen
Ten (10) normal adult male subjects were asked to move a known weight, representing 15% of the maximal lifted weight, in both horizontal and vertical conditions at frequencies of 40 cycles/min and 60 cycles/min. Raw EMG signals from six (6) shoulder muscles were recorded and synchronized with the cinematographic data during three (3) trials of six (6) seconds each. The raw EMG signals of each muscle were full wave rectified and filtered at three (3) Hz. The LE EMG signals were normalized by time (% cycle) and by amplitude (% MVC), and for the analysis of variance, the normalized LE EMG signals were integrated (IN LE EMG). The average shoulder angular velocities, joint moments and moment powers were computed from cinematographical data. No significant difference were observed between both tasks for the supraspinatus, infraspinatus, and pectoralis major IN LE EMG data as well as for integrated normalized shoulder joint moment for the whole cycle of movement. IN LE EMG data from middle deltoid, anterior deltoid, and trapezius muscles were significantly higher (p 0.05) when performing the vertical displacement task for the whole cycle of movement. (Abstract shortened by UMI.)
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MacLean, Janet. "The time course of healing of myocardial infarct in pigs". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5744.
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Gaudet, Pierre. "Relationship between heart rate and blood lactate responses to a sport specific field test in elite male and female badminton players". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5816.
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No statistically significant difference between genders was observed. Among all the comparisons of the 30 second intervals within the 5 minute HRREC data, only two time periods were not statistically significant. One was early in recovery and one was late in recovery. Mean BLa went down every minute from 6.91 mMol at post 1 minute to 6.51 mMol at post 5 minute but this difference was not statistically significant. No statistically significant correlation were found to exist between HRREC and BLaREC. However, PEAKBLa following the test was correlated with HRREC measurements such that the following two trends were found. First, the correlation between PEAKBLa and the absolute HR values obtained at different time intervals during recovery became stronger with increasing time up to the 2nd minute of recovery and second, PEAKBLa was negatively correlated with 5 minute HRREC. PEAKBLa was negatively correlated with the HRREC obtained in the first two minutes of recovery but this relation became positive between the 2nd and 5th minute of recovery. (Abstract shortened by UMI.)
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Ablack, David. "The effect of selected rest intervals on total work volume and blood lactate levels during high intensity elbow flexion exercise at a fixed relative resistance". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5969.
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A group of male subjects (N = 8) were used to examine the effects of two selected rest intervals on total work volume and blood lactate during a maximal effort elbow flexion resistance exercise performed at a fixed relative resistance (70% IRM). The rest intervals were set at 30 seconds (R$\sb{30}$) and 180 seconds (R$\sb{180}$) and were based on the half and full recovery times respectively of the high energy creatine phosphate (CP) system. The exercise continued until a computerized light sensor system detected a movement speed decrease to a pre-determined level of fatigue. R$\sb{180}$ resulted in a significantly greater volume of work (247%) achieved without a statistically significant increase in blood lactate (10%) compared to R$\sb{30}$. It was concluded that a rest interval between repeats of elbow flexion exercise of 180 seconds versus 30 seconds significantly increased the ability to do work without a significant increase in the contribution of the anaerobic lactic system. (Abstract shortened by UMI.)
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Villemure, Christiane. "The role of corticosterone in the defective control of brown adipose tissue thermogenesis in mice with gold thioglucose-induced obesity". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5983.
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Gold thioglucose (GTG) leads to hypothalamic obesity in mice. The purpose of this study was to determine if hypersensitivity to corticosterone is present in mice with hypothalamic obesity. Mice were injected with either saline or GTG and sham-adrenalectomized or adrenalectomized (adx). The adx animals received cholesterol implants containing corticosterone. Certain abnormalities of GTG-mice, namely hyperphagia, increased white adipose tissue and brown adipose tissue (BAT) weights and hyperinsulinemia are normalized by adrenalectomy and returned in virtually full force at low levels of corticosterone. Other abnormalities like high body weight and reduced BAT mitochondrial GDP binding are not affected. BAT protein was not affected by adrenalectomy in either lean or obese animals and was reduced by corticosterone replacement in both. It is concluded that GTG-mice are hypersensitive to an action of corticosterone which plays an important role in the development of their obesity. However, some abnormalities, like the suppressed BAT thermogenesis, persist in the adx state and seem to be due to metabolic defects primarily caused by the GTG lesions that are not dependent on corticosterone. (Abstract shortened by UMI.)
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Rouleau, Michèle. "Cellular and cytoskeletal heterogeneity along the rat ventral prostatic duct". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5991.
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In this study, the ductal heterogeneity in the rat ventral prostate was further investigated in terms of structural elements that make up the different cell types of the prostate as well as cell populations found along prostatic ducts. In addition, effects of androgens were analyzed in specific locations of the ductal-acinar network. The cytokeratin content of the prostate was characterized biochemically and by immunofluorescence and was used as a marker to monitor the behaviour of each cell type after androgen depletion. It was found that the cytokeratin content of basal and luminal epithelial cells are characteristic for each cell type and that these structural proteins constitute good markers for these cell types. Using antibodies specific for basal and luminal epithelial cells, the ratio basal to luminal epithelial cells was shown to vary along the prostatic duct as well as after castration, suggesting a preferential loss of luminal epithelial cells. Based on the observations of the cellular dynamics in the prostate of intact versus castrated rats, a model of regression is proposed. (Abstract shortened by UMI.)
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Brady, Marcus Evan. "In vivo quantitation of the phosphorus-containing metabolites in rat hind limb by nuclear magnetic resonance spectroscopy during four weeks of creatine depletion induced by feeding beta-guanidinopropionic acid". Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/6026.
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Bensimon, Michael A. "Heterotrimeric G(i/o) proteins regulate stretch-stimulated ANF secretion in isolated rat atria". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6073.
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Atrial wall stretch plays an important role in regulating the secretion of ANF, a cardiac peptide hormone that regulates water and salt balance, as well as blood pressure. Yet the precise cellular mechanism that couples mechanical stretch to ANF secretion is unknown. In order to elucidate this mechanism, we investigated the role of heterotrimeric Gi/o proteins in mechanically-stimulated ANF secretion. G proteins act as molecular switches that have been implicated in the control of intracellular protein transport, and stretch-secretion coupling. We utilized a pharmalogical agent, pertussis toxin (PTX), to inhibit Gi/o proteins in male Sprague Dawley rats. The effect of stimulating Gi/o proteins was also investigated using Mastoparan-7 (MAS-7; 10-5 M). Infusion with MAS-7 for 30 minutes potently stimulated ANF secretion; a response attenuated by. Results suggest that Gi/o proteins couple atrial muscle stretch to ANF secretion in an acute setting, and that there exist two mechanisms, which control natriuretic peptide secretion. The first mechanism controls stretch-stimulated ANF secretion and is PTX-sensitive, while the second regulates basal ANF release and is PTX-insensitive. (Abstract shortened by UMI.)
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Lapner, Katherine Nancy. "Catecholamine secretion during hypoxia in nicotinic receptor-desensitised rainbow trout, Oncorhynchus mykiss". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6149.
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Experiments were performed in vivo using an extra-corporeal blood loop (EC-loop), on chronically cannulated adult rainbow trout ( Oncorhynchus mykiss) to determine whether the ability of fish to respond to acute hypoxia was impaired by an intravenous nicotine infusion (1.3 x 10-5 mol kg-1 h -1; designed to desensitise chromaffin nicotinic receptors). Respiratory and cardiovascular measurements taken throughout the nicotine infusion of the desensitisation protocol indicate that non-chromaffin, neuronal nicotinic receptors also appear to be stimulated and to desensitise. The next set of experiments showed that despite nicotinic receptor desensitisation induced by intravenous infusion of nicotine, plasma catecholamine levels were increased to similar levels (adrenaline plus noradrenaline = 125--200 nmol l-1) as in control fish during severe hypoxia (40--45 mm Hg). (Abstract shortened by UMI.)
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Patenaude, Sonia I. "Structural studies of the biosynthesis and recognition of the human ABO(H) blood group antigens". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6188.
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High-resolution crystal structures of the human ABO blood group glycosyltransferase enzymes, unliganded and in complex with substrate molecules, reveal the basis for their substrate specificity and suggest amino acid residues important in catalysis. The human ABO(H) blood group glycosyltransferases differ in only 4 amino acid residues and are therefore two of the most homologous, naturally occurring glycosyltransferases known that utilize different naturally occurring donor molecules. An N-acetylgalactosaminyltransferase (GTA) uses a UDP-GalNAc donor to convert the H-antigen to the A-antigen, while a galactosyltransferase (GTB) uses a UDP-Gal donor to convert the H-antigen to B antigen. The resulting A and B blood group antigens differ from each other only in the substitution on the terminal saccharide residue of an acetamido for an hydroxyl group yet the potentially catastrophic effects of a mismatched blood transfusion makes them a paradigm for specificity in biosynthetic and immune recognition. The crystal structures of the catalytic domains of the cloned blood-group A and B enzymes have been determined to 1.80 and 1.65 A resolution, respectively, and those of the catalytic domains of the A and B enzymes in complex with the H antigen disaccharide and UDP to 1.35 and 1.32 A resolution, respectively. Glycosyltransferases that retain the stereochemistry of the donor sugar, such as GTA and GTB, have been postulated to function via a double-inversion mechanism, including a nucleophilic attack on the donor sugar anomeric carbon. The current structures support the double inversion mechanism and reveal, remarkably, that only two of the amino acids differing between GTA and GTB are positioned to select between the two donors and thus contribute to the stringent stereo- and regioselectivity in this biosynthesis. In addition, the structures of GTA and GTB in complex with H antigen alone have been determined to 1.58 and 1.46 A resolution, respectively, and show that, contrary to expectations, the acceptor substrate can bind in the absence of the donor substrate. The DxD motif in GTA and GTB coordinates a manganese ion, which in turn interacts with the UDP-sugar donor. Comparison of the GTA and GTB structures to the other two retaining glycosyltransferases (bovine alpha1-3galactosyltransferase, N. meningitidis LgtC) structures determined to date reveals that the coordination between the aspartate residues and manganese ion are the same. Interestingly, this coordination pattern is different from those observed in inverting glycosyltransferases, suggesting that these patterns may be characteristic of inverting versus retaining glycosyltranserases. The structure of an antibody fragment specific for the human blood group A trisaccharide antigen has also been determined to near-atomic resolution. This structure shows a pronounced pocket at the antigen-binding site, which is formed by four of the six complementarity determining regions, and is of the appropriate size and shape to accommodate the terminal N-acetylgalactosamine residue of the A trisaccharide antigen. A model of the Fv-trisaccharide complex shows several protein-carbohydrate interactions that would allow specific recognition of the blood group A antigen acetamido group.
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Lortie, Michel B. "The rainbow trout muscle beta(2)-adrenoceptor system: Impact of beta(2)-agonist feeding". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6268.
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Previous studies showed that beta2-adrenergic agonists (beta 2-AAs) enhanced muscle growth and reduced lipid deposition in animals of agricultural and economical importance, including teleost fish. The goal of the present study was to provide a mechanistic explanation underlying the reported beta2-AA-induced muscle growth in the rainbow trout (Oncorhynchus mykiss). Using radioligand binding assays and adenylyl cyclase/cAMP assays, this study characterized and demonstrated the presence of functional beta2-adrenoceptors (beta2-ARs) on red and white muscle membranes. Trout fed 40 ppm of two beta2-AAs (clenbuterol and ractopamine) for 30 days showed no significant changes in measured body and physiological parameters, beta2-AR numbers or beta2-AR mRNA levels in red or white muscle. However, treatments significantly increased fractional protein synthesis rates in red and white muscle. These studies demonstrate that beta2-AAs impact muscle protein synthesis by mechanisms initiated at the muscle membrane beta 2-AR and include the beta2-AR-signalling pathway in a teleost fish.
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Fortin, Yves D. "Lower extremity muscle function during ergometer rowing". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6617.
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The purpose of this study was to determine the functional role of six prominent leg muscles during knee extension. Changes in muscle-tendon length and EMG activity were looked at in conjunction with the results from an inverse dynamics analysis. The muscles investigated were the monoarticular vastus lateralis, soleus, gluteus maximus and the biarticular biceps femoris, rectus femoris and gastrocnemius. Four female and five male elite rowers performed on a Gjessing rowing ergometer while kinematic information was recorded on cinefilm. The force applied to the stretcher, the force applied to the oar handle and the EMG activity were sampled simultaneously. Through inverse dynamics, net moments of force at the ankle, knee and hip joints and powers from these moments were computed for one drive. The results showed a difference in the use of knee extensors by female and male rowers. For the females, the power produced originated exclusively from the hip extensors. This contrasts with the results obtained from the male subjects where power was produced by hip and knee extensors. Plausible explanations include differences in anatomical structures between both sexes (skeletal dimensions, tendon attachments location, muscle mass distribution), differences in rowing technique and deficiency in the knee extensor strength. Paradoxical activity appeared to take place in the recruitment of the biarticular gastrocnemius and biceps femoris during the extension of the knee. More intriguing was the detection of paradoxical activity from the action of m. rectus femoris at the hip which it seemed to extend.
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Keefe, Allan. "The effects of carbon dioxide on sleep and thermoregulation in cold environments". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6620.
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In order to study the effects of mild hypercapnia on sleep and thermoregulation, 5 male volunteers (23.6 +/- 1.96 yrs) were exposed to air containing 0, 2, or 4% CO2, while sleeping in a double (9.0 clo) or single (4.5 clo) Canadian Forces sleeping ensemble (1 clo = 0.155°C·m 2·W-1) at -20°C. Each condition was presented twice in a completely randomized manner on non-consecutive nights. Standard polysomnographic EEG, EMG and EOG measures were monitored as well as rectal (Tr), mean skin (T¯sk) and toe (T toe) temperatures. Hypercapnia was associated with enhanced body cooling as indicated by a decreased time to minimal Tr and Ttoe (p < .05). In agreement with current knowledge of sleep in cold environments, sleeping in the single bag resulted in a significantly decreased percentage of REM sleep (p < .05) and trends towards decreases sleep efficiency and total sleep time (TST). Slow wave sleep (%SWS) tended to increase in the single bag condition. CO2 exposure was associated with a trend towards decreased TST and suppression of the cold induced increase in %SWS. The possible effects of body temperatures being mediated through sleep processes as opposed to direct CO2 effects, and the possible importance of SWS on thermoregulation were discussed.
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Rollin, Hélène. "Le ratio taille/hanches et le niveau de pratique d'activité physique comme indicateurs des taux de HDL et LDL chez les hommes hypercholestérolémiques". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6642.
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Par cette recherche, nous voulons verifier si en ajoutant une mesure de ratio taille/hanches et une mesure du niveau de pratique d'activite physique aux activites regulieres de depistage de facteurs de risque de maladie cardiovasculaire, nous pourrons ameliorer notre capacite d'identifier les individus qui ont un risque accru de developper cette maladie. La litterature demontre les liens qui existent entre l'obesite abdominale determinee par le ratio taille/hanches, le niveau de pratique d'activite physique et les taux de HDL et de LDL. On reconnait egalement, qu'un taux de HDL inferieur a 0,9mmol/L et/ou qu'un taux de LDL superieur a 3,4 mmol/L jumeles a un taux de cholesterol total superieur ou egal a 5,2mmol/L constitue un risque accru de developper une maladie cardiovasculaire. Soixante-et-un (61) sujets masculins ages entre 35 et 64 ans ont participe a cette recherche. On a recueilli aupres de ceux-ci, de donnees de ratio taille/hanches, d'habitudes de vie, de pratique d'activite physique ainsi que des mesures de poids, taille et pression arterielle et des mesures sanguines de cholesterol total, de HDL, de LDL et de triglycerides. Les analyses de variance et le test de Tukey ne nous demontrent pas l'existence de differences significatives, des taux de HDL et LDL, entre les groupes d'hommes hypercholesterolemiques sedentaires et actifs et entre les hommes hypercholesterolemiques ayant un ratio taille/hanches eleve et bas.
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Liu, Yuning. "Pressor response to isometric handgrip combined with foot immersion in cold water". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6701.
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The purposes of this study were to (1) compare the pressor response between isometric exercise and a cold pressor test (CPT) and (2) examine the pressor response to isometric exercise at 33% of maximal voluntary contraction (MVC) combined with a CPT applied either at the onset or during the last minute of a 2-min CPT. Ten normotensive male volunteers performed isometric handgrip (HG) at 33% MVC, cold foot immersion, HG combined with a simultaneous CPT, and HG performed during the last minute of a 2-min CPT in a random order over three days. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) were recorded at rest and continuously throughout the tests. The results of this study indicate that (1) the pattern of HR response between the 2-min HG and the CPT was different; (2) DBP values during CPT for the initial 30s and the last 15s were significantly lower than DBP corresponding values during HG, while there were no significant differences between the CPT and HG with respect to SBP response; (3) when HG and CPT were performed simultaneously, the effects on SBP and HR were additive, whereas the effects on DBP and MAP were not; (4) CPT performed for 1 minute prior to HG attenuated the SBP and HR responses to HG at 33% MVC, and (5) although both HR and BP increased in response to HG at 33% MVC, only BP increased progressively in a linear fashion when combined with CPT. (Abstract shortened by UMI.)
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Komorowski, Joanna Irena. "Influence of protein kinase C activators and inhibitors on rat granulosa cell steroidogenesis in vitro". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6745.
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The present studies were undertaken to determine the involvement of protein kinase C (PKC) in the regulation of rat granulosa cell steroidogenesis in vitro. The effects of PKC activators (1-oleoyl-2-acetylglycerol (OAG); 1,2-dioctanoylglycerol (DiC$\sb8$) and phorbol 12-myristate 13-acetate (TPA)) and inhibitors (DL-Sphingosine (ESP) and 1-(5-Isoquinolinylsulfonyl)-3-methylpiperazine free base (H$\sb7)\rbrack$ on basal and FSH-, (Bu)$\sb2$cAMP-, forskolin- and calcium ionophore A23187-stimulated pregnenolone (P$\sb5$), progesterone (P) and 20$\alpha$-hydroxy-pregn-4-en-3-one (20$\alpha$-OH-P) secretion by granulosa cells were studied. OAG, when continually present in the culture medium (MEM), significantly stimulated P$\sb5$, P and 20$\alpha$-OH-P secretion during 6 to 24 h culture periods. It also markedly increased the conversion of exogenous P$\sb5$ to P and 20$\alpha$-OH-P and exogenous P to 20$\alpha$-OH-P during 24 h cultures. Pretreatment of granulosa cells with TPA for 1 h or treatment for up to 6 h resulted in a significant increase in P$\sb5$, P and 20$\alpha$-OH-P secretion. Except for 20$\alpha$-OH-P production, which was stimulated by the phorbol ester during all culture periods studied, secretion of P$\sb5$ and P (in the presence or absence of exogenous hormones and the inhibitors of steroidogenic enzymes) were substantially inhibited by TPA during a 24 h incubation. However, when granulosa cells were incubated with both OAG (20 $\mu$g/ml) and TPA (40 ng/ml), progestin secretion was increased irrespective of the duration of incubation. PKC inhibitors dose-dependently suppressed the stimulatory effect of OAG (20 $\mu$g/ml) and TPA (40 ng/ml) with complete inhibition noted at 100 $\mu$M of H$\sb7$ and 10 $\mu$M of ESP. Diacylglycerols and TPA exerted divergent effects on FSH-, (Bu)$\sb2$cAMP- and forskolin-stimulated progestin secretion. FSH-stimulated accumulation of P$\sb5$ throughout the culture periods (1-24 h) was markedly increased by OAG (20 $\mu$g/ml) but inhibited by TPA (40 ng/ml). OAG (5-80 $\mu$g/ml) and DiC$\sb8$ (20 $\mu$g/ml) significantly enhanced FSH-induced progestin secretion during 6 h and 24 h culture periods and increased steroid synthesis in 24 h cultures in the presence of (Bu)$\sb2$cAMP or forskolin. In contrast, TPA significantly inhibited FSH- and (Bu)$\sb2$cAMP-stimulated progestin secretion during both 6 h and 24 h of incubation. Pretreatment of granulosa cells with TPA (40 ng/ml) for 20 h to down-regulate PKC, decreased progestin secretion during subsequent incubation with FSH (150 ng/ml) and prevented any stimulation by OAG (20 $\mu$g/ml). The effects of OAG (20 $\mu$g/ml) and TPA (40 ng/ml) on FSH-induced steroid secretion appeared to be additive when both PKC activators were present together and differed significantly from those when OAG and TPA were present with FSH separately. Diolein (a nonpermeable diacylglycerol), 4$\alpha$-phorbol 12,13-didecanoate and phorbol 13-monoacetate (two phorbol esters with no tumor promoting activity) did not influence basal or FSH-stimulated steroid secretion by granulosa cells. (Abstract shortened by UMI.)
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McKay, Andrea J. "Potassium infusion in chronic potassium depleted rats rapidly reverses defective thick ascending limb chloride reabsorption by an aldosterone independent mechanism". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6753.
Texto completoResumen
Previous studies from our laboratory, using a modified loop microperfusion technique (microstop-flow conductivity) in vivo, have shown that NaCl transport by the thick ascending limb (TAL) is impaired in potassium depleted (K-DEP) rats. The degree of impairment in TAL NaCl transport is highly correlated with plasma potassium (K$\sp+$) concentration and is completely reversed when extracellular fluid potassium concentration (ECF (K$\sp+$)) is increased by acute potassium infusion. These experiments assessed NaCl transport by the TAL in the absence of axial flow by measuring the conductivity of tubular fluid emerging from an early distal tubule site after different intervals of stop-flow (10-60 seconds) in perfused nephrons. Since these measurements of TAL transport were made in the absence of axial flow, the significance of the defect in NaCl transport in K-DEP rats could not be determined under in vivo conditions of physiological flow and chloride (Cl$\sp-$) delivery. To determine the quantitative importance of this impairment in NaCl transport by the TAL, Cl$\sp-$ reabsorption was measured in functionally isolated perfused single loops of Henle in vivo, using the technique of continuous microperfusion. Cl$\sp-$ reabsorption was measured in loop segments microperfused at 22 nL/minute using a modified perfusate which minimized proximal nephron transport. This modification of the loop perfusate allowed the measurement of furosemide-sensitive Cl$\sp-$ reabsorption in the perfused loop segments such that net Cl$\sp-$ uptake in this study can be attributed primarily to carrier-mediated Cl$\sp-$ transport by the TAL. Others have provided evidence that TAL NaCl reabsorption is aldosterone dependent in adrenalectomized animals. In our rats given a K-free diet, both plasma (K$\sp+$) and plasma (aldosterone) were significantly reduced. Since aldosterone release is regulated by ECF (K$\sp+$), the purpose of the present study was to determine whether an aldosterone deficiency and/or reduced ECF (K$\sp+$) mediates inhibition of TAL Cl$\sp-$ transport in potassium depletion. Using the described microperfusion conditions, it was possible to show that the defect in TAL Cl$\sp-$ reabsorption in K-DEP rats was quantitatively significant and can be rapidly reversed by the acute systemic infusion of potassium. Acute administration of aldosterone, in the presence of sustained hypokalemia, failed to reverse the impairment in TAL Cl$\sp-$ reabsorption in K-DEP rats. However, the acute infusion of potassium, in the presence of an aldosterone antagonist, in K-DEP rats rapidly reversed the defect in TAL Cl$\sp-$ reabsorption to control levels. Additional studies showed that despite normalization of ECF (K$\sp+$) by acute potassium infusion in K-DEP rats, aldosterone levels failed to increase to control levels within this time period. This is the first study to demonstrate that the restoration of plasma (K$\sp+$) in K-DEP rats is not immediately associated with a parallel rise in plasma (aldosterone). As well, new knowledge was obtained from the present studies which showed that although a minimal (aldosterone) is required for normal TAL Cl$\sp-$ transport to occur, this steroid hormone does not regulate Cl$\sp-$ reabsorption by this nephron segment. Therefore, these results provide conclusive evidence that in K-DEP rats the rapid reversal of defective TAL Cl$\sp-$ reabsorption seen with acute potassium infusion occurs via an aldosterone independent mechanism.
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Zampini, Daniela Zardini. "Characterization of type IIX muscle fibres in the mouse". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6775.
Texto completoResumen
The properties of type IIX fibres in mouse skeletal muscle and the factors affecting the expression of myosin heavy chain (MHC) in these fibres were studied. Type IIX fibres were recognized on the basis of a lack of staining with antibodies directed against type I, IIA and IIB MHC. The IIX MHC isoform contained a determinant common to all type II MHCs, but lacked epitopes specific for types IIA and IIB MHCs, as well as an epitope that was present in all other MHCs. Fibres expressing IIX MHC accounted for about one-third of the total fibre number in mouse fast-twitch muscles. Sciatic nerve crush with subsequent reinnervation resulted in the formation of "type IIX fibre groups" in tibialis anterior and gastrocnemius, suggesting that the IIX phenotype is neurally regulated. The association of specific MHC isoforms with individual fibre types was confirmed by gel electrophoresis. Using 5%, 6% and 3-5% gradient sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) IIX MHC was found to co-migrate with IIA MHC. Immunohistochemistry and gel electrophoresis of single fibres from the superficial part of the tibialis anterior muscle (TAS) showed the existence of hybrid fibres co-expressing IIB and IIX MHC. Myosin light chain (MLC) analysis of IIX fibres revealed the presence in these fibres of MLC 3f in amounts significantly smaller than that contained in IIB fibre types which suggests that type IIX fibres have a lower Vo than type IIB fibres. Physiological, histochemical and morphometrical properties of fast-twitch single motor units were studied. Single motor units were functionally isolated by microdissection of the ventral root, the glycogen depletion technique was used to demonstrate the muscle fibres in the motor unit and monoclonal antibodies were used to identify their MHC composition in order to correlate physiological, histochemical and morphometrical studies. These studies revealed that IIX motor units had contractile properties similar to those of types IIA and IIB motor units but had morphological, physiological and biochemical properties that distinguish them from the latter two types. IIX motor units had a resistance to fatigue, cross-sectional fibre area and motor unit area intermediate between IIA and IIB motor units. Finally, the effect of altered thyroid hormone status and age on the expression of IIX MHC was studied. Hypothyroidism led to a decrease in the expression of IIB MHC and an increase of IIX MHC in TAS muscle, while hyperthyroidism had no significant effect. The proportion of type IIX and IIB fibres in TAS muscle of the mouse undergoes specific age-related changes that can not be detected with conventional histochemical techniques. Specifically, the proportion of fibres expressing IIB MHC decreased and the proportion of fibres expressing type IIX and co-expressing type IIB and IIX MHC increased with age. It is proposed that fibres co-expressing IIX and IIB MHC represent a transitional fibre type involved in an age-related transformation process.
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Bindon, Shawn. "Interrelationship between chloride cell proliferation and gas transfer in the rainbow trout". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6797.
Texto completoResumen
This thesis examines the morphological and physiological changes that occur in the gills of the rainbow trout, Oncorhynchus mykiss, as a result of chloride cell proliferation. In the first component of this thesis (Chapter 2), the effects of chloride cell hyperplasia and hypertrophy on ion transport capability and the morphological diffusing capacity of the gill were evaluated. These experiments were performed to test the hypothesis that chloride cell proliferation benefits ionic regulation at the expense of efficient gas transfer. Concomitant with the surface morphology results, significant increases in Na$\sp+$ (J$\rm\sb{in}Na\sp+)$ and Cl$\sp-$ uptake (J$\rm\sb{in}Cl\sp-)$ were observed following treatment with the individual combined hormone regimens. Conversely, the gas morphological diffusion capacity, as indicated by the morphological parameters measured, of hormone treated fish was reduced, and was inversely correlated to chloride cell fractional surface area. Surface morphometric analysis showed that the hormone treatment increased the average chloride cell surface area by 2.7 x and chloride cell density by 2.2 x; the combined effect was a five-fold increase in chloride cell fractional area. While the P$\rm\sb aO\sb2$ values of hormone-treated and control fish were similar at P$\rm\sb wO\sb2>12.0$ kPa, the arterial O$\sb2$ tensions of treated fish were significantly lower than those of the control group for P$\rm\sb wO\sb2\leq12.0$ kPa. In comparison, to control fish at all environmental O$\sb2$ tensions, the hormone-treated fish exhibited elevated P$\rm\sb aCO\sb2$ values and a significant acidosis. The effects of chloride cell proliferation on blood gas parameters in hormone-treated fish were accompanied by significantly elevated ventilation amplitudes and lowered ventilation frequency. (Abstract shortened by UMI.)
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McKay, Allison E. "Gastroduodenal motility during the development of experimental duodenal ulceration: The effects of enteric transmitters and anti-ulcer drugs". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6809.
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Mangat, Harman. "A study of stretch-stimulated ANF release from the atrial myocardium". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6833.
Texto completoResumen
Atrial muscle stretch is widely believed to be the main stimulus for ANF release. However, we demonstrate in this study that although stretch induces an immediate increase in ANF output, this release rapidly decays even though hormone stores are not significantly depleted. In the present work, this phenomenon was studied in an isolated rat atria preparation using double isotope labelling. The tissue was labelled with $\rm\sp C$-leucine for 3 h followed by a 1 h chase, and then with $\rm\sp3H$-leucine for 1 h. A final 1 h chase period was conducted with the tissue under basal (0.2 g load) or stretched (5 g load) conditions. During this final chase period, the $\rm\sp C$-ANF represented ""older", stored ANF and the $\rm\sp3H$-ANF the "newly synthesized" peptide. Following both the $\rm\sp C$- and $\rm\sp3H$-leucine pulses, immunoprecipitable (IP) isotope incorporated into ANF appeared in the chase medium within the first 10 min and stabilized to lower levels after 20 min of chase. Stretch resulted in an immediate significant increase in immunoreactive (ir) ANF release and a decrease in the medium $\rm\sp C$-ANF specific activity (S.A.). However, no change was observed in the medium $\rm\sp3H$-ANF S.A. but the tissue S.A. tended to decrease. It is concluded that, in the basal state, a portion of ANF is immediately and preferentially released upon synthesis, while the remainder is presumably taken up into tissue stores and released from them at a lower rate. The secretory response to stretch was demonstrated to consist of a rapid, short-lived burst of newly synthesized ANF, suggesting an increased translocation of newly synthesized hormone into a stretch-sensitive, rapidly depletable pool. Given the nature of this pool, additional factors yet to be characterized likely come into play to maintain chronically elevated circulating levels of ANF.
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Lins, Otavio G. "Ocular artifacts in recording EEGs and event related potentials". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6889.
Texto completoResumen
The ocular artifacts derive from the potential difference between the cornea and the fundus of the eye. This can be represented by an equivalent dipole with its positive pole directed toward the cornea. The DC potential between the cornea and the forehead measures approximately +13 mV. The scalp-distribution of the ocular artifacts can be described in terms of propagation factors--the percentage of the EOG present at the EEG electrodes. These factors are significantly different for blinks and upward eye-movements. The source dipoles for blinks and saccades are different--blink dipoles point radially whereas saccade dipoles point tangentially, in the direction of the eye movement. Blink and eye movement potentials are generated by different mechanisms--blink potentials are generated by the eyelid sliding over the cornea, eye movement potentials by the rotation of the ocular dipole. A very small downward rotation of the eyes may occur during a normal blink. The "rider artifact" at the onset of upward saccade is caused by the eyelid as it lags behind the eyes at the beginning of the movement. Smaller rider artifacts, caused by the horizontal asymmetry of the eyelid, can be noted during horizontal but not downward saccades. Techniques that use scaled EOG to remove ocular artifacts from EEG recordings may remove some of the frontal EEG together with the ocular artifacts. Dipole source techniques allow the ocular generators to be distinguished from the nearby brain generators. A problem with dipole source techniques is that the head model used in the calculation is not accurate at the eyes. A new technique uses principal component analysis to estimate the ocular artifact at each electrode without using a head model. This technique is the most effective way to remove ocular artifacts from EEG recordings. (Abstract shortened by UMI.)
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Cicutti, Nicholas. "Applications of the colored microsphere technique in the mammalian coronary microcirculation". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6896.
Texto completoResumen
The aim of this dissertation was to provide realistic descriptions of two unique properties of the mammalian coronary microcirculation using our novel application of colored microspheres in myocardium. One important objective was to provide an innovative approach to investigate the controversial issue of whether individual coronary arteries communicate at the microvascular level, thus potentially giving rise to a zone of dual arterial supply. Simultaneous in vivo infusion of two distinctly colored microsphere suspensions into the left anterior descending (LAD; red spheres) and left circumflex (LCx; blue spheres) arteries identified a specific interface region of canine myocardium perfused by both arterial branches. Two distinct zones were delineated, and their widths measured. One region was defined as the Interface Transition Zone (ITZ). This region was formed by microvessels supplied by the individual parent arteries, and separated tissue containing only one or the other colored microspheres. The second region defined as the Boundary Watershed Zone (BWZ) was formed by capillaries containing sphere aggregates of both colors; it was located exclusively within the ITZ. In addition, the ITZ and BWZ were significantly wider in subepicardial than in subendocardial regions. Our subsequent study investigated the potential lability of the coronary watershed zones. As before, two differently colored microsphere suspensions were infused into the LAD (red spheres) and LCx (blue spheres) arteries of nine dogs. Subsequently, the LAD was ligated and a third set (green) of spheres was infused into the LCx. Capillaries perfused exclusively by the LAD before occlusion adjacent to the interface contained green microspheres as well as red/green aggregates, indicating lateral extension of the LCx perfusion territory. Results showed that occlusion caused a 24% expansion of the ITZ and a 48% expansion of the BWZ. In addition, all expansions were significantly greater in subepicardial compared to subendocardial regions. These results demonstrated the capability of microvascular anastomoses in providing blood flow to the periphery of an ischemic region. We also applied our colored microsphere technique for the characterization of coronary capillary flow direction in rat myocardium. Our initial study determined capillary flow direction in two groups of male Sprague-Dawley rats: (1) pressure overload hypertrophy and (2) sham-operated controls. Chronic pressure overload was induced in neonatal rats by aortic constriction. Six weeks postsurgery, both groups received sequential in vivo infusion of two differently colored microsphere suspensions into the left atrial appendage. Histological analysis of 40 $\mu$m serial sections revealed that certain coronary capillaries contained microspheres of both colors. A capillary flow vector was established based on the sequence of colors trapped within each aggregate. Examination of flow vectors among neighboring capillaries enabled the characterization of regional capillary flow direction. Results indicated a predominance in concurrent flow, which decreased significantly over a range of capillary rankings. The percentage of concurrent flow was also significantly lower in subendocardium compared with midmyocardium. This study provided previously unattainable data regarding transmural capillary flow direction and suggested regional adaptations in coronary microvascular flow. (Abstract shortened by UMI.)
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Small, Daniel L. "The potentiating effects of neuropeptide Y on vascular smooth muscle". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7461.
Texto completoResumen
In the present study, the roles of nifedipine-sensitive calcium channels and the endothelium in the potentiating effect of neuropeptide Y (NPY) in the rat tail artery were investigated. Contractile responses to KCl, $\alpha,\beta$-methylene ATP (mATP), and NA were compared. KCl- and mATP-induced vasoconstriction is closely linked to nifedipine-sensitive calcium channels while NA-induced vasoconstriction is not. The role of the endothelium in potentiating effects of NPY was also tested by comparing intact arterial ring segments with denuded arterial ring segments. Freshly isolated single smooth muscle cells in which the influences of the endothelium and the nerves were unequivocally eliminated were examined to verify the results of the ring segments. Contractile responses to KCl and mATP were potentiated by NPY (50 nM) while NA responses were not potentiated at 50 nM but were at 500 nM NPY. The potentiating effect of NPY was antagonized by nifedipine. The intact and denuded arteries responded similarly. The shortening of single smooth muscle cells in response to KCl and mATP was potentiated by NPY (50 nM) while the noradrenaline response was potentiated by NPY at 500 nM but not at 50 nM. (Abstract shortened by UMI.)
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Vanderluit, Jacqueline L. "The effect of dynamic exercise on the blood pressure response to isometric exercise in normotensive males". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7527.
Texto completoResumen
The purpose of this study was to determine whether the pressor response to a static handgrip exercise would be blunted if performed during or immediately following dynamic exercise. Male subjects performed one minute handgrip (HG) contractions under three conditions (1) standing at rest, (2) during the 4th to 5th min of treadmill walking exercise and (3) during recovery one min following the combined exercise. The handgrip exercises were performed at 30% and 40% of maximum voluntary contraction (MVC). The results indicated that there was a main effect of intensity, such that HG exercises performed at 40% MVC produced a significantly greater blood pressure response than HG at 30% MVC for all three conditions. The systolic response to static exercise is blunted when a HG at 30% MVC is performed during moderate dynamic exercise but not with HG contractions at 40% MVC. In addition, the systolic response to static exercise is also blunted when HG contractions at both 30% and 40% MVC are performed following dynamic exercise. Also, dynamic exercise augments the diastolic response to static contractions (30% & 40% MVC) performed following dynamic effort. (Abstract shortened by UMI.)
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Paradis, Hilje K. "Osmoregulation in uncontrolled diabetes mellitus". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7568.
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In this thesis we studied the influence of osmotic loading on vasopressin secretion and water intake in experimentally-induced diabetes mellitus, in the insulin deprived state as well as when treated with insulin, in order to investigate whether the osmotic drive for vasopressin release and thirst is altered in the diabetic state. Four dogs were used for the experiments to be reported. They were infused with hypertonic sodium sulfate to investigate the influence of osmotic loading on water intake and vasopressin secretion in the control, insulin-treated diabetic and diabetic conditions. Forty-eight hours of insulin depletion did not produce a change in the basal plasma vasopressin levels, even though there was a significant increase in plasma osmolality. In addition, forty-eight hours of insulin depletion did not alter the sensitivity of the osmoreceptors controlling vasopressin release and thirst. The effect of the diabetic condition on the osmotic threshold is subject to interpretation of the data. If glucose is considered an osmotically effective solute in the diabetic state, there is an upward resetting of the osmostat for vasopressin release and thirst, and a downward or leftward shift of the osmostat when glucose is not considered to be effective osmotically. The results of the present study provide evidence that the osmotic sensitivity of vasopressin release and thirst is not affected by the presence or absence of insulin. However, whether there is a true resetting of the osmostat for vasopressin release and thirst in the diabetic state depends on the assumption mode concerning glucose permeability.
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Eley, Douglas W. "Mechanisms involved in the disruption and restoration of excitation-contraction coupling in the rat myocardium by hypochlorous acid and dithiothreitol". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7601.
Texto completoResumen
In the present studies, the addition of HOCl to the bathing medium for isometrically contracting papillary rat papillary muscles induced the development of contracture. This was characterized by a decline in developed tension (DT) in combination with a rise in resting tension (RT), a prolongation in relaxation kinetics, and a sensitivity of the muscles to stimulation voltage. This response to HOCl was potentiated by preincubation with low extracellular Ca$\sp{2+}$ or the Ca$\sp{2+}$ channel antagonist nifedipine. Conversely, the response was attenuated by preincubation with high extracellular Ca$\sp{2+}$ concentrations or with the Ca$\sp{2+}$ channel agonist Bay K 8644. The development of contracture was prevented by preincubation with 1 nM ryanodine, an alkaloid compound known to alter Ca$\sp{2+}$ handling by the sarcoplasmic reticulum. In isolated whole-cell clamped cardiac myocytes, using the Ca$\sp{2+}$ fluorescence indicator Fura-2 to monitor (Ca$\sp{2+}$) $\sb{\rm i}$, HOCl induced a steady rise in diastolic (Ca$\sp{2+}$) $\sb{\rm i}$ even in the absence of extracellular Ca$\sp{2+}$. This rise in (Ca$\sp{2+}$) $\sb{\rm i}$ was prevented by pre-exposure of the cell to 5 mM caffeine, a compound known to deplete the SR of stored Ca$\sp{2+}$. In oxalate loaded SR vesicles isolated from rat hearts perfused with HOCl, both the activity of the SR Ca$\sp{2+}$-ATPase (determined by inorganic phosphate production) and the uptake of $\sp{45}$Ca$\sp{2+}$ were significantly depressed as compared to Control. I conclude that the exposure of the rat myocardium to HOCl inactivates the SR Ca$\sp{2+}$-ATPase through the oxidation of protein thiols, leading to a cytosolic Ca$\sp{2+}$ overload and the development of contracture. Cursery evidence also suggests that the Ca$\sp{2+}$ pump of the sarcolemma and the Na$\sp+$/Ca$\sp{2+}$ exchanger may also be inactivated. Subsequent exposure of the HOCl-treated myocardium to the disulfide reducing agent dithiothreitol (DTT) resulted in a restoration of contractile function, characterized by a decline in RT concomitant with a recovery of DT in the isolated papillary model, or a recovery of left ventricular end diastolic pressure and developed pressure in the perfused rat heart. We conclude that DTT was able to cross cellular membranes where it restored cellular protein thiol levels by reducing HOCl-induced disulfide formation. (Abstract shortened by UMI.)
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Keon, Claudia Anne. "Ionic, metabolic and contractile function changes in the isolated rat heart during ischemia and reperfusion: Lithium-7, sodium-23 and phosphorus-31 NMR spectroscopy studies". Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7638.
Texto completoResumen
$\sp7$Li NMR spectroscopy has been used to investigate the transsarcolemmal transport mechanisms responsible for the increase in intracellular sodium that occurs during global ischemia in the isolated rat heart. Hearts were perfused with a modified Krebs Henseleit buffer containing 78 mM sodium and 78 mM lithium, lithium being a biological congener for sodium with twice the sodium NMR sensitivity. The NMR relaxation times for lithium were investigated in the perfused heart and buffer solutions. The addition of the shift reagent, DyTTHA$\sp{3-}$, shortened the relaxation times for lithium in buffer and enabled the discrimination of intra- and extracellular lithium. Lithium moved into the myocardial cells with a rate constant (k$\sb{-1}$) of 0.068 min$\sp{-1}$, a t$\sb{1/2}$ of 10.3 min and an initial rate of increase of 5.27 mM/min, while lithium noved out of the heart with a k$\sb{-1}$ of 0.062 min$\sp{-1}$, a t$\sb{1/2}$ of 11.2 min and an initial rate of 4.83 mM/min. Lithium equilibrated in the heart with equal concentrations on either side of the sarcolemma, not in equilibrium with its electrochemical gradient. Perfusion with the low-sodium, lithium-containing buffer had a positive inotropic effect on the heart with no effect on the steady state levels of the myocardial high energy phosphates. The myocardial rate pressure product increased by 114% while the ATP and PCr concentrations, measured using $\sp{31}$P NMR spectroscopy, varied by less than 8%. ICP-AES analysis of hearts showed that as lithium accumulated in the cells, it displaced both sodium and potassium. Finally, intracellular lithium increased during myocardial ischemia with a linear rate of 1.34 mM/min, similar to the rate of increase of intracellular sodium during ischemia. This increase was completely blocked by the Na$\sp+$/ H$\sp+$ exchange inhibitor, amiloride. (Abstract shortened by UMI.)
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Andersen, Donald E. "Metabolic effects associated with chronically elevated cortisol in rainbow trout (Oncorhynchus mykiss)". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/7714.
Texto completoResumen
The metabolic role of chronically elevated cortisol in otherwise unstressed rainbow trout, Oncorhynchus mykiss, was examined. Fish were fitted with mini-osmotic pumps which maintained plasma cortisol levels at approximately 100 or 200 ng $\cdot$ mL$\sp{-1}$ for ten days. Plasma metabolites, liver enzyme activities, liver glycogen content, metabolic flux in isolated hepatocytes and alanine turnover were investigated. Plasma glucose, lactate and protein levels were unaffected by ten days of cortisol administration, despite a significant elevation in plasma cortisol. Plasma amino acids in cortisol treated fish (1023.8 $\pm$ 90.7 $\rm\mu g\cdot mL\sp{-1})$ were significantly elevated compared to shams $\rm(716.7\pm68.5\ \mu g\cdot mL\sp{-1})$ after nine days. Liver glycogen content was significantly reduced by cortisol treatment. The activities of the liver enzymes assayed were unchanged; likewise the fluxes of radioactive substrates to radiolabelled CO$\sb2,$ glucose, and protein in isolated hepatocytes were unaffected in trout with chronically elevated cortisol compared to shams. Both the caloric and water contents of white muscle were unaffected by chronically elevated circulating cortisol levels. The cortisol treatment did not alter the turnover of alanine. These data do not support the purported role of cortisol as a glucocorticoid in rainbow trout. While chronically elevated cortisol may increase the supply of plasma amino acids, the hormone does not appear to alter the manner in which these potential gluconeogenic substrates are metabolized. The absence of other stressors may be partially responsible for the differences between this study and others in the literature.
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Saumure, Nancy E. "The effects of leg cycling training on lactate threshold and maximal oxygen consumption measured during leg cycling and arm cranking exercise". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7752.
Texto completoResumen
The purpose of this study was to determine if the training effects on lactate threshold (LT) and maximal oxygen consumption (VO$\sb2$max) are specific to musculature involved in training or if there is evidence of a general training effect, such that adaptations are also found during exercise with untrained muscle groups. Seven moderately active male students participated in an eight week progressive endurance training program that involved leg cycling at specific intensities above and below the pre-training LT to give a total of 30 minutes of training above LT three times per week. All subjects were tested before and after training for LT and VO$\sb2$max while performing leg cycling and arm cranking exercises. VO$\sb2$max showed a significant increase during both leg cycling and arm cranking exercise following training. Conversely, increases in both absolute and relative LT were confined to leg cycling exercise only. It is suggested that peripheral adaptive responses of oxidative capacity within the trained muscles are primarily responsible for the specificity of the LT response, while cardiovascular adaptations were beneficial to VO$\sb2$max of both of the muscle groups tested. Furthermore, the significant improvement in relative LT during leg cycling and of VO$\sb2$max to both arm and leg exercise suggests that adaptive responses of LT and VO$\sb2$max to training are not governed by the same physiological processes. Therefore, it was concluded that, for the conditions of this experiment, the concept of specificity of training applies to LT but not to VO$\sb2$max when comparing exercise modalities which involve separate musculature.
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Lang, Mia E. "Intestinal permeability in the irradiated ferret". Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7772.
Texto completoResumen
Ferrets received whole-body irradiation (5 Gy, gamma). At different times post-irradiation (PIRR, 2, 24, and 48 hours), measurements of fluid and electrolyte fluxes, and of the blood-to-lumen clearance of $\sp{51}$Cr-EDTA, were compared between in situ perfused loops of jejunum and ileum. Intestinal permeation of $\sp{51}$Cr-EDTA was increased (4x control) in both the jejunum and ileum at 2 hours PIRR. At 24 hours PIRR, $\sp{51}$Cr-EDTA permeation was the same as control. At 48 hours PIRR, jejunal permeation of $\sp{51}$Cr-EDTA was not statistically different from control animals, whereas in the ileum, $\sp{51}$Cr-EDTA permeation was increased 10x control. Absorption of luminal fluid was abolished 2 hours PIRR in the ileum. Sodium and chloride fluxes were unaffected by radiation exposure, but at 48 hours PIRR there was a significant secretion of potassium in the ileum. Diarrhea rarely occurred after the first hour post-irradiation. Serotonin, acting via 5-HT$\sb3$ receptors, was investigated as a possible mediator of radiation-induced alterations in intestinal permeability. Pretreatment with the 5-HT$\sb3$ antagonist and anti-emetic BRL 43694 significantly reduced the severity of radiation-induced vomiting. It offered some therapeutic benefit to radiation-induced diarrhea. However BRL 43694 pretreatment had no effect on intestinal permeability. (Abstract shortened by UMI.)