601 |
L’apprentissage par situation complexe en EPS au collège, rôles de la coopération et de la compétition en natation de vitesse chez des élèves de 5ème / Learning by complex situation in Physical Education (PE), role of cooperation and competition in speed swimming for 8th grade collège students.Le Briquer, Yannick 22 December 2017 (has links)
Ce travail examine les bénéfices d’un apprentissage par situation complexe en natation de vitesse chez des élèves de 5ème ; les soubassements théoriques sont pluriels. L’Approche Par Compétence (APC) à l’école, selon la pédagogie de l’intégration, invite à concevoir des situations complexes conduisant les élèves à intégrer leurs ressources pour résoudre des problèmes. Cette approche pédagogique se base aussi sur la psychologie sociale du développement et des acquisitions plaçant au coeur des dispositifs d’apprentissage, les interactions sociales et les échanges verbaux. Plus précisément, le dispositif étudié est construit à partir des principes socioconstructivistes de l’apprentissage coopératif. Au cours d’une séquence de douze séances d’EPS, les élèves de deux conditions d’enseignement différentes, ont été testés de façon répétée en situation complexe. Ce travail poursuit trois objectifs. En premier lieu, nous avons comparé les acquisitions sur les plans moteur, social et méthodologique, des élèves selon la condition (individuelle / interactive). Les résultats révèlent des progrès plus importants au niveau des performances chronométriques pour les élèves de la condition interactive. Ensuite, nous avons examiné le processus de « mise en synergie » des ressources, induit par la situation complexe. Etre préparé à intégrer ses ressources en situation complexe, optimise le développement de compétences motrices, cognitives et sociales. Enfin, nos observations dévoilent les effets de la compétition sur la coopération des élèves. L’apprentissage par situation complexe optimise l’exploitation des compétences individuelles au profit de la réalisation d’une performance collective. / This work examines the advantages of training in speed swimming complex situations for 8th grade pupils and there are many theoretical bases attached to it. The competencies-based approach (APC in French) at school, according to the pedagogy of integration, invites to conceive complex situations leading pupils to integrate their resources to solve problems. This teaching approach is also based on the development and acquisition social psychology putting forward training devices, social interactions and verbal exchanges. More precisely, this work is built according to the socioconstructivist principles of the co-operative learning. During a sequence of twelve PE sessions, two groups of pupils in two different teaching conditions, were tested in complex situations. This work pursues three goals. Initially, we compared pupils according to the condition (individual/interactive), their acquisitions on the physical, social and methodological levels. The results reveal more important progress on the level of chronometric performances for the pupils of the interactive condition. Then, we examined the resources, induced by the complex situation in the process of “setting in synergy”. To be prepared to integrate his complex situation resources optimizes the development of physical, cognitive and social skills. Lastly, our observations reveal the effects of competition on the pupils’ co-operation. The training by complex situation optimizes the coordination of individual skills to succeed in the collective performance.
|
602 |
Self-organisation of confined active matterWioland, Hugo January 2015 (has links)
Active matter theory studies the collective behaviour of self-propelled organisms or objects. Although the field has made great progress in the past decade, little is known of the role played by confinement and surfaces. This thesis analyses the self-organisation of dense bacterial suspensions in three different microchambers: flattened drops, racetracks and lattices of cavities. Suspensions of swimming bacteria are well-known to spontaneously form macroscopic quasi-turbulent patterns such as jets and swirls. Confinement inside flattened drops and racetracks stabilises their motion into a spiral vortex and wavy streams, respectively. We have quantitatively measured and analysed bacterial circulation and discovered cells at the interfaces to move against the bulk. To understand this phenomenon, we developed a method able to measure simultaneously the directions of swimming and of motion. Experiments in drops reveal that cells align in a helical pattern, facing outward and against the main bulk circulation. Likewise, bacteria in racetracks share a biased orientation against the overall stream. Particle-based simulations confirm these results and identify hydrodynamic interactions as the main driving force: bacteria generate long-range fluid flows which advect the suspension in the bulk against its swimming direction, resulting in the double-circulation pattern. We have finally injected dense suspensions of bacteria into lattices of cavities. They form a single vortex in each cavity, initially spinning clockwise or counterclockwise with equal probabilities. Changing the topology of the lattice and the geometry of connections between cavities allows us to control the lattice state (random, ferromagnetic, antiferromagnetic, or unstable). Edge currents along interfaces and connections appear to determine the lattice organisation. We finally propose an Ising model to understand experimental results and estimate Hamiltonian and interactions parameters. This work opens new perspectives for the study of active matter and, we hope, will have a great impact on the field.
|
603 |
Stability of self-propelled body wake / Stabilité du sillage d'un corps auto-propulséArbie, Muhammad Rizqie 14 December 2016 (has links)
La nageoire caudale des animaux aquatiques peut être modélisée par un foil oscillant qui produit de la poussée. Le sillage moyen d'un tel foil oscillant est un jet de quantité de mouvement nette positive. Il a été proposé que les caractéristiques de stabilité de ces sillages moyens sont liées à l'efficacité de la propulsion des animaux aquatiques. Dans cet étude, nous reprenons cette question en tenant compte à la fois de la poussée et de la traînée exercée sur un corps auto-propulsé lorsqu'il nage. Nous étudions la stabilité d'une famille de sillages ayant une quantité de mouvement nulle, construit comme l'approximation d'Oseen d'un doublet de force se déplaçant à vitesse constante. En effectuant une analyse de stabilité locale, nous montrons d'abord que ces sillages subissent une transition convectif-absolu. En utilisant une approche "time-stepper" et intégrant le système de Navier-Stokes linéarisé, nous étudions la stabilité globale et mettons en évidence des effets non-parallèles de l'écoulement principal, ainsi que le rôle de la région absolument instable dans l'écoulement. Pour compléter le scénario d'instabilité globale, nous abordons l'évolution non linéaire d'une perturbation injectée dans le sillage. Ces résultats sont ensuite discutés dans le contexte de la nage d'un animal aquatique. Selon les résultats de stabilité, les sillages de quantité de mouvement nulle produit par les animaux aquatiques sont généralement stables, tandis que le sillage qui correspondrait à la poussée seule est instable. Il est essentiel de considérer toutes les forces exercées sur un animal auto-propulsé lors de l'examen de la stabilité de son sillage et l'efficacité de sa propulsion. / The caudal fin of swimming animals can be modelled as a thrust-producing flapping foil. When considered alone, such a foil produces on average a jet wake with a positive net momentum. It has been argued that the instability characteristics of these averaged wakes are linked to the propulsion efficiency of swimming animals. Here, we reconsider this question by taking into account both the thrust and the drag exerted on a self-propelled swimming body. To do so, we study the stability of a family of momentumless wakes, constructed as the Oseen approximation of a force doublet moving at constant velocity. By performing a local stability analysis, we first show that these wakes undergo a transition from absolute to convective instability. Then, using the time-stepper approach by integrating the linearised Navier-Stokes system, we investigate the global stability and reveal the influence of a non-parallel base flow as well as the role of the locally absolutely unstable upstream region in the wake. Finally, to complete the global scenario, we address the nonlinear evolution of the wake disturbance. These results are then discussed in the context of aquatic locomotion. According to the present stability results, the momentumless wake of aquatic animals is generally stable, whereas the corresponding thrust part is unstable. It is therefore essential to consider all forces exerted on a self-propelled animal when discussing its wake stability and its propulsion efficiency.
|
604 |
Swimming in four goldfish (Carassius auratus) morphotypes: understanding functional design and performance through artificial selectionLi, Jason 05 1900 (has links)
Although artificially selected goldfish exhibit swimming performance decrements, with the most derived morphotypes more affected, they can be utilized to explore functional design and movement pattern principles in aquatic vertebrates. Drag, steady swimming kinematics (tailbeat frequency, amplitude, stride length), energetics (standard and active metabolic rate), fast-start performance (average and maximum velocity and acceleration), stability in yaw and roll and propulsive muscle ultrastructural characteristics (mitochondrial volume density and spacing, myofibril diameter and capillary to fibre ratio in red and white muscle) were measured for four morphotypes: common, comet, fantail and eggfish, of comparable length (≈ 5 cm). A performance “pairing” (common and comet; fantail and eggfish) was a recurrent theme for most performance parameters. Vertebral numbers (30), segment lengths (≈ 0.85 mm) and standard metabolic rates (≈ 140 mg O2 kg-1 hr-1) are exceptions where values are the same. Fantail and eggfish drag and drag coefficients (referenced to frontally projected area ≈ 0.6 - 0.9) were higher (requiring more thrust at any given velocity) than those for the more streamlined common and comet (≈ 0.3 - 0.6; P < 0.05). This is reflected in kinematics; tailbeat frequency and stride length at any given velocity for the common and comet are lower and higher respectively than that of the fantail and eggfish (P < 0.05). Common and comet fatigue times are not significantly different from that of their ancestor, Crucian carp (P > 0.05), and are lower than those of the fantail and eggfish (P < 0.05). The cost of transport of the common and comet (≈ 0.6 mg O2 kg-1 m-1) is accurately predicted from the mass scaling relationship for fish (P > 0.05), but values for the fantail and eggfish (≈ 1.3 mg O2 kg-1 m-1) are not (P < 0.05). Eggfish steady swimming (dorsal fin absent) was characterized by rolling and yawing motions associated with significant energy losses. Common and comet fast-start performance (average velocity ≈ 0.45 m s-1, maximum velocity ≈ 1.2 m s-1, average acceleration ≈ 7.5 m s-2, maximum acceleration ≈ 35 m s-2) was similar to that of other locomotor generalists (e.g. trout). Eggfish maximum acceleration (≈ 5 m s-2) is poor due to the absence of inertial and lifting contributions to thrust from the dorsal fin and energy wasting rolling motions. Artificially selected fish can bear upon fitness related adaptations associated with form and movement, providing insights into the “performance envelope” of natural systems subject to ecological speciation. / Science, Faculty of / Zoology, Department of / Graduate
|
605 |
Glucose Kinetics of Hyperglycemic Rainbow Trout: Effects of Exogenous Glucose and ExerciseChoi, Kevin January 2015 (has links)
This thesis investigates the ability of rainbow trout to modulate hepatic glucose production (Ra) and disposal (Rd). My goals were to determine: (1) if resting trout can modulate fluxes to cope with exogenous glucose; (2) how fluxes change during graded swimming; (3) how exogenous glucose affects swimming kinetics; and (4) if exogenous glucose affects cost of transport or performance. Results show that resting trout suppress Ra completely and stimulate Rd from 10.6 to 27.6 μmol kg-1 min-1. During swimming, fluxes increase from 15.6 to 21.9 μmol kg-1 min-1, but only at speeds >2.4 BL s-1. When given glucose, trout suppress Ra from 16.4 to 4.1 μmol kg-1 min-1 and stimulate Rd from 16.4 to 40.1 μmol kg-1 min-1. Glucose lowers metabolic rate but does not affect critical swimming speed. Therefore, this research shows that rainbow trout have a much better capacity for glucoregulation than generally suggested by current literature.
|
606 |
Endocannabinoid Modulation of Post-Ischemia DepressionBonneville, Marika January 2016 (has links)
Post-ischemia depression (PID) is a condition that affects approximately 30% of survivors from stroke or cardiac arrest and has an important impact on patients’ quality of life. Previous studies support important roles of the endocannabinoid (eCB) system in depression and brain ischemia. This study attempts to link all three variables together by investigating the role and mechanism of eCB signaling in the development of PID. A global ischemia + hypotension model was used to induce a PID phenotype in CD1 mice. Three ischemic time frames were tested, and even though all three could induce significant cell death in the CA1 region of the hippocampus, only the 15-minute time point led to an increased immobility time on the forced swimming test (FST). The main goal of this study was to investigate the effect of a cannabinoid type-I receptor (CB1R) antagonist/inverse agonist, AM281, on the development of two depressive symptoms: anhedonia, measured with the sucrose preference test (SPT), and behavioral despair, measured with the FST. AM281 administration was able to significantly reduce the symptoms of anhedonia and behavioural despair. Subsequently, the mechanism behind this antidepressant-like effect was investigated. Administration of bicuculine with AM281 did not significantly affect the antidepressant effect on the FST, therefore suggesting that AM281 does not act on GABAergic synapses. A similar protocol was adopted with NVP-AM077, where its administration combined with AM281 was able to block the effect of AM281, thus confirming the importance of glutamatergic synapses for the antidepressant effect of AM281. Furthermore, the administration of a TAT-GLUR2 peptide did not significantly affect the effect of AM281, implying that the astroglial cell-mediated LTD (long-term depression) at glutamatergic synapses is not involved in the antidepressant effects of AM281. Finally, a bilateral intra-BLA (basolateral nucleus of the amygdala) administration of AM281 was able to reduce the immobility time on the FST. In conclusion, these results highlight the important contribution of BLA glutamatergic synapses to the antidepressant-like effect conferred by AM281.
|
607 |
Prédiction de la performance en natation par les mesures d'activité du Système Nerveux Autonome : modélisation mathématique / Prediction of performance in swimming by Autonomic Nervous System activity assessment : mathematical modelingChalencon, Sébastien 07 June 2013 (has links)
Durant ces 20 dernières années, de nombreuses études réalisées chez l’homme ont mis en évidence l’utilité de la Variabilité de la Fréquence Cardiaque (VFC) comme outil d’investigation de l’activité du Système Nerveux Autonome (SNA). Des études longitudinales et transversales ont par ailleurs démontré des relations fortes entre SNA, entrainement et performance. La recherche d’indicateurs biologiques permettant au mieux de paramétrer la charge d’entraînement a conduit à l’étude de différents paramètres parmi lesquels la VFC. L’objectif de l’ensemble de ce travail de thèse a été, à la fois, l’étude de la prédiction de la performance en natation ainsi que la modélisation des effets de l’entraînement sur le SNA. L’étude I modélise les effets de l’entraînement sur l’activité parasympathique au travers du modèle de Banister, initialement conçu pour représenter les effets de l’entraînement sur la performance. Une relation significative de type logarithmique est démontrée, également, entre l’activité parasympathique et la performance. L’étude II démontre la pertinence de la VFC dans le pilotage et l’optimisation de la charge d’entraînement. Cette étude a utilisé les paramètres issus des modèles linéaire et non-linéaire des 10 nageurs pour analyser l’influence sur la performance et l’activité parasympathique de la charge d’entraînement. Cette étude rend compte de l’application pratique de la modélisation mathématique et des simulations informatiques dans la prédiction de la performance et l’optimisation de la charge d’entraînement en vue de maximiser à la fois les gains de performance et d’activité parasympathique. L’ensemble de ce travail démontre, au travers de la modélisation mathématique des réponses à l’entraînement de l’activité parasympathique et sa confrontation aux réponses de la performance, que la puissance spectrale en HF est un outil non invasif et facilement utilisable en routine pour optimiser l’entraînement. Au-delà de la démonstration d’une relation significative, c’est la mise en évidence d’une évolution en phase de ce paramètre physiologique et de la performance qui a été démontrée / Over the past 20 years, numerous studies in humans have demonstrated the usefulness of Heart Rate Variability (HRV) as a tool for investigating the activity of Autonomic Nervous System (ANS). Longitudinal and transversal studies have also shown a strong relationship between ANS activity, training load and performance. Monitoring of the training load has led to the study of various physiological parameters including the HRV. The goal of all this work was the study of the abilities of ANS parameters to predict the level of performance in swimming, as well as, modeling the effects of training load on the parameters of ANS. Study I models the effects of training on parasympathetic activity through the Banister model, originally designed to represent the effects of training on performance. A significant logarithmic relationship was demonstrated between parasympathetic activity and performance. Study II demonstrates the relevance of HRV and mathematical modeling to drive and optimize the training load. This study, using model parameters calculated from linear and non-linear mathematical formulation for 10 swimmers, analyzes the ability of computer simulation to predict performance and parasympathetic activity in response to the training load. The results demonstrate the practical application of mathematical modeling and computer simulations in predicting the performance and optimization of the training load to maximize both performance gains and parasympathetic activity All this work demonstrates, through mathematical modeling, the relevance of HF spectral power of HRV as a non-invasive tool, easy to use in routine, to optimize the training load and predict the performance in swimming. Beyond the demonstration of a significant relationship between parasympathetic activity and performance, it was an evolution in phase of these two parameters that was highlighted
|
608 |
Swimming PoolNilsson, Linette January 2017 (has links)
My project started with two words: Swimming Pool. They came to me through a song, Banshee Beat by Animal Collective (2005). To me, their music is mystical, abstract, unpredictable and also metaphorical. So I started to think about if a swimming pool could be something more than just an open container filled with water. After some thinking I came to the conclusion that it could be a metaphor for something calm, quiet and dreamy. However, I’m not sure but my aim is not to get to a specific answer through this project. I’ll turn the metaphor into a textile work that portrays what you see when you’re standing at the edge of the swimming pool; a distorted picture of a grid, the bottom of the pool. I’ll be working with dyeing, patchwork and quilting. The textile craft is important in this project because of how relaxed and calm I get by doing things with my hands. The questions I’m asking myself are how I can express the metaphor through my work? What if my interpretation is too wide? Is it possible for me to create a tactile and calm feeling without the physical touch?
|
609 |
Oscillation d'une plaque flexible dans un écoulement / Oscillation of a flexible plate in a flowParaz, Florine 09 July 2015 (has links)
La physique de nage d’une nageoire caudale flexible est étudiée expérimentalement grâce à une plaque flexible immergée dans un écoulement uniforme. Le bord d’attaque est forcé par un mouvement harmonique, tandis que le bord de fuite répond passivement au forçage. Une résonance en amplitude dans la réponse est mise en évidence et révèle une forte interaction entre les fréquences naturelles de la plaque et celles du forçage. Les résultats expérimentaux suggèrent un rôle non trivial de l’amplitude de forçage, qui souligne le rôle des non linéarités dans ce problème. Pour avoir une meilleure compréhension de l'origine de ces non linéarités, un modèle analytique faiblement non linéaire a été développé. Nous supposons une plaque d'épaisseur nulle immergée dans un écoulement potentiel, sujette à une force de traînée résistive. La déflection de la plaque a ensuite été décomposée en un mode rigide, mimant le forçage en pilonnement et en modes propres de flexion d’une poutre dans le vide. Les prédictions de la réponse en amplitude et en fréquence du système forcé sont alors calculées. Les fréquences de résonances, ainsi que l’enveloppe de la déflection, sont en bon accord avec les résultats expérimentaux. Les performances du système, mesurées à travers la poussée générée, est également correctement prédite par la modélisation. L’accord entre les expériences et le modèle est étendu à une étude trouvée dans la littérature. Une optimisation analytique a été conduite et étendue à l’application de la bio-robotique. / The physics of the swimming with a flexible caudal fin is studied experimentally by the means of an elastic plate immersed in a uniform water flow. The leading edge of the plate is forced into a harmonic motion, while its trailing edge responds passively to this actuation. A resonance response in amplitude is demonstrated, revealing a strong interaction between the natural frequencies of the plate and the forcing frequencies. Experimental results suggest a non-trivial role of the forcing amplitude, emphasizing the role of non linearities in this problem. To gain better insight into the origin of these non linearities, a weakly non linear model is developed. We model a quasi two-dimensional plate of zero thickness immersed in a potential flow and subject to a resistive drag-like force. The plate deflection is then decomposed into a forcing heaving mode and natural flexural modes. Predictions of the response in amplitude and frequency to a heave forcing system are then calculated. The frequencies of the resonances, as well as the shapes of the deflection, match the experimental results. The performance of the system measured through the generated thrust, is well predicted by the modelling. The experimental and modelling results presented here show (very) good agreement with the literature. Finally, an analytical optimization is undertaken and potential applications to bio-robotic are suggested.
|
610 |
Efeito da intensidade do estresse sobre marcadores metabolicos / Effect of stress intensity on metabolic markersHatore, Edgar Teruhiko 25 October 2006 (has links)
Orientadores: Regina Celia Spadari-Bratfisch, Dora Maria Grassi-Kassisse / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-07T15:56:51Z (GMT). No. of bitstreams: 1
Hatore_EdgarTeruhiko_M.pdf: 10729043 bytes, checksum: a8e99d57d617133d73cabb8f544052b9 (MD5)
Previous issue date: 2006 / Resumo: Os efeitos do estresse por natação sobre marcadores metabólicos diferem daqueles do estresse por choques nas patas. Estas diferenças poderiam ser conseqüências da natureza do estressor, que difere nos dois modelos, ou da intensidade de estresse, que parece ser menor quando os animais são submetidos à natação do que quando submetidos a choque nas patas. O objetivo deste trabalho é avaliar o efeito da intensidade do estressor sobre a mobilização de substratos metabólicos. Ratos Wistar adultos foram distribuídos em grupos: controle, não submetido à natação; e ratos submetidos à natação em água a 35°C, 24°C ou 18°C. As sessões de natação ocorreram em três dias consecutivos com 5, 15 e 15 min de duração, respectivamente. Os ratos foram pesados antes da primeira e da última sessão de natação e após a última sessão sua temperatura retal foi determinada por um tele-termômetro; foram anestesiados e uma amostra de sangue foi coletada por punção cardíaca. Foram retiradas amostras do fígado e dos músculos gastrocnêmio, sóleo e ventricular cardíaco. Adipócitos foram isolados do tecido adiposo epididimal e incubados com agonistas adrenérgicos. O glicerol e o lactato liberados no meio infranadante foram considerados como indicadores da sensibilidade das respostas lipolítica e glicolítica aos agonistas, respectivamente. Foram determinadas também as concentrações plasmáticas de glicose, lactato, ácidos graxos livres, glicerol e corticosterona, além da concentração muscular e hepática de glicogênio. O peso corporal dos ratos dos quatro grupos não apresentou diferença estatisticamente significativa antes da primeira ou da terceira sessão de natação. Após natação em temperaturas de 24°C e 18°C os ratos apresentaram hipotermia (30,7 +/- 0,7°C e 24,0 +/- 0,5°C, respectivamente) em relação os grupos controle (37,2 +/- O,12°C) e natação a 35°C(36,7 +/- 0,2°C), entre os quais não houve diferença estatisticamente significativa. Após a terceira sessão de natação, a concentração plasmática de corticosterona aumentou significativamente nos grupos submetidos à natação em 18°C (294,7 +/-17,9 ng/mL) e 24°C (289,5 +/- 27,1 ng/mL) do que 35°C (166,3 +/- 11,8 ng/mL), sendo os três significativamente diferentes do controle (57,2 +/- 10,0 ng/mL), enquanto que as concentrações sanguíneas de lactato e de ácidos graxos livres estavam significativamente elevadas em relação ao controle, mas não diferiram entre os grupos de ratos submetidos à natação. As concentrações de glicogênio das amostras hepáticas, cardíacas e do músculo sóleo de ratos submetidos à natação não diferiram significantemente do grupo controle. Porém, as concentrações de glicogênio nas porções branca e vermelha do músculo gastrocnêmio estavam reduzidas após natação. Em adipócitos isolados de ratos submetidos à natação houve aumento da liberação basal de glicerol e de lactato, mas as respostas ao d-butiril-AMPc, à noradrenalina e à adrenalina, assim como a sensibilidade às duas catecolaminas,não diferiu significantemente do controle. Concluímos que a intensidade do agente estressor pode ser modulada pela temperatura da água em protocolos de estresse por natação, de modo que as temperaturas mais baixas em relação à temperatura corporal do rato determinam respostas de estresse mais intensas, evidenciadas pela concentração plasmática de corticosterona. Entretanto, as alterações observadas nos marcadores metabólicos analisados são independentes da intensidade do estressor, no paradigma de estresse utilizado neste trabalho / Abstract: The effects of swimming stress on metabolic markers are different than those induced by foot-shock stress. These differences might be due either to stress intensity, which seems to be minor when the rats are submitted to swimming than foot-shock stress, or to the type of stressor agent. The aim of this work is to evaluate the effect of the stressor intensity on metabolic markers. Adult Wistar rats were distributed in groups: control, not submitted to swimming; or swimming stressed rats with the water temperature at 35°C, 24°C or 18°C. Swimming sessions occurred daily, for 3 days, with 5, 15 and 15 min duration, respectively. Before the first and last sessions the rats were weight and after the last swimming session the rat's rectal temperature was determined using a tele-thermometer; then the rats were anesthetized and a blood sample was collected through cardiac puncture. Samples of the liver, as well as the gastrocnemius, soleus and cardiac muscles were also collected. Adipocytes were isolated from the epididimal adipose tissue and were incubated with adrenergic agonists: The glycerol and lactate released in the infranatant were considered as indicative of in vitro lipolytic and glycolytic sensitivity to the agonists,respectively. The plasma concentrations of glucose, lactate, free fat acids, glycerol and corticosterone, as well as the muscular and hepatic glycogen concentrations were determined. The results have shown that the rat' s body weights were not altered by swimming. After swimming at 24 C and 18 C the rats showed severe hypothermia (30.7+/-0.7°C and 24.0+/- 0.5 C, respectively, p<0.05), whereas swimming at 35C did not alter the rats rectal temperature (36.7 +/-0.2°C) compared to control (37.2 +/- 0.12C). The plasma levels of corticosterone significantly enhanced in 18°C (294.7 +/- 17.9 ng/mL), 24°C (289.5+/- 27.1 ng/mL) and 35°C (166.3 +/-11.8 ng/mL) swimming groups, compared to control (57.2 +/- 10.0 ng/mL). The glucose and glycerol plasma levels were not altered, whereas the blood lactate and free fat acids levels significantly increased after swimming, with no difference between the stressed groups. Swimming did not alter the glycogen concentrations of the liver as well as cardiac and soleus muscle, but caused a decrease in the white and red gastrocnemius compared to control, with the decrease being independent of the water temperature. The in vitro basal glycerol and lactate release by adipocytes increased, similarly in all swimming groups. The lipolytic response to d-butiryl cAMP,norepinephrine and epinephrine were not different between groups. Catecholamines determined a biphasic effect on lactate release by adipocytes with the concentrations in the range up to 10 nM being stimulant and those higher than 10 nM being inhibitory of lactate release. No differences were observed between groups. We conclude that the stress intensity might be modulated by the water temperature in protocols of swimming stress, with lower temperatures being more stressful than those similar to the rats body temperature, as determined by the plasma levels of corticosterone. We also conclude that the swimming stress paradigm altered the analyzed metabolic markers in a manner that was independent of the stressor intensity (homotypic), in the stress paradigm used in this work / Mestrado / Fisiologia / Mestre em Biologia Funcional e Molecular
|
Page generated in 0.0706 seconds