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Marc-antoine Custaud - One of the best experts on this subject based on the ideXlab platform.
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Multi-System Deconditioning in 3-Day Dry Immersion without Daily Raise
Frontiers Media S.A., 2017Co-Authors: Steven De Abreu, Guillemette Gauquelin-koch, Francoise Larcher, Liubov Amirova, Ronan Murphy, Robert Wallace, Laura Twomey, Veronique Raverot, Marc-antoine CustaudAbstract:Dry immersion (DI) is a Russian-developed, ground-based model to study the physiological effects of microgravity. It accurately reproduces environmental conditions of weightlessness, such as enhanced physical inactivity, suppression of hydrostatic pressure and supportlessness. We aimed to study the integrative physiological responses to a 3-day strict DI protocol in 12 healthy men, and to assess the extent of multi-system Deconditioning. We recorded general clinical data, biological data and evaluated body fluid changes. Cardiovascular Deconditioning was evaluated using orthostatic tolerance tests (Lower Body Negative Pressure + tilt and progressive tilt). Metabolic state was tested with oral glucose tolerance test. Muscular Deconditioning was assessed via muscle tone measurement.Results: Orthostatic tolerance time dropped from 27 ± 1 to 9 ± 2 min after DI. Significant impairment in glucose tolerance was observed. Net insulin response increased by 72 ± 23% on the third day of DI compared to baseline. Global leg muscle tone was approximately 10% reduced under immersion. Day-night changes in temperature, heart rate and blood pressure were preserved on the third day of DI. Day-night variations of urinary K+ diminished, beginning at the second day of immersion, while 24-h K+ excretion remained stable throughout. Urinary cortisol and melatonin metabolite increased with DI, although within normal limits. A positive correlation was observed between lumbar pain intensity, estimated on the second day of DI, and mean 24-h urinary cortisol under DI. In conclusion, DI represents an accurate and rapid model of gravitational Deconditioning. The extent of glucose tolerance impairment may be linked to constant enhanced muscle inactivity. Muscle tone reduction may reflect the reaction of postural muscles to withdrawal of support. Relatively modest increases in cortisol suggest that DI induces a moderate stress effect. In prospect, this advanced ground-based model is extremely suited to test countermeasures for microgravity-induced Deconditioning and physical inactivity-related pathologies
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body fluid changes Cardiovascular Deconditioning and metabolic impairment are reversed 24 hours after a 5 day dry immersion
Open Journal of Nephrology, 2013Co-Authors: Mickael Coupe, I M Larina, Guillemette Gauquelinkoch, Vladimir A. Kulchitsky, E S Tomilovskaya, Francoise Larcher, Bertrand Diquet, Liudmila Pastushkova, I B Kozlovskaya, Marc-antoine CustaudAbstract:Dry immersion is an effective and useful model for research in physiology and physiopathology. The focus of this study was to provide integrative insight into renal, endocrine, circulatory, autonomic and metabolic effects of dry immersion. We assessed if the principal changes were restored within 24 h of recovery, and determined which changes were mainly associated with immersion-induced orthostatic intolerance. Five-day dry immersion without countermeasures, and with ad libitum water intake, standardized diet and a permitted short daily rise was performed in a relatively large sample for this experiment type (14 healthy young men). Reduction of total body water derived mostly from extracellular compartment, and stabilized rapidly at the new operating point. Decrease in plasma volume was estimated at 20% - 25%. Five-day immersion was sufficient to impair metabolism with a decrease in glucose tolerance and hypercholesterolemia, but was not associated with pronounced autonomic changes. Five-day immersion induced marked Cardiovascular impairment. Immediately after immersion, over half of the subjects were unable to accomplish the 20-min 70° tilt; during tilt, heart rate and total peripheral resistance were increased, and stroke volume was decreased. However, 24 hours of normal physical activity appeared sufficient to reverse orthostatic tolerance and all signs of Cardiovascular impairment, and to restitute plasma volume and extracellular fluid volume. Similarly, metabolic impairment was restored. In our study, the major factor responsible for orthostatic intolerance appeared to be hypovolemia. The absence of pronounced autonomic dysfunction might be explained by relatively short duration of dry immersion and daily short-time orthostatic stimulation.
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low magnitude whole body vibration with resistive exercise as a countermeasure against Cardiovascular Deconditioning after 60 days of head down bed rest
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2011Co-Authors: Mickael Coupe, Claire Demiot, Guillemette Gauquelinkoch, Ming Yuan, Yanqiang Q Bai, Shizhong Z Jiang, Philippe Arbeille, Thibaud Levrard, Marc-antoine CustaudAbstract:Whole body vibration with resistive exercise is a promising countermeasure against some weightlessness-induced dysfunctions. Our objective was to study whether the combination of low-magnitude whol...
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Enforced physical inactivity increases endothelial microparticle levels in healthy volunteers.
AJP - Heart and Circulatory Physiology, 2010Co-Authors: Nastassia M Navasiolava, Florence Sabatier, Irina M Larina, Claire Demiot, Jacques-olivier Fortrat, Guillemette Gauquelin-koch, Inesa B Kozlovskaya, Marc-antoine CustaudAbstract:A sedentary lifestyle has adverse effects on the Cardiovascular system, including impaired endothelial functions. Subjecting healthy men to 7 days of dry immersion (DI) presented a unique opportunity to analyze the specific effects of enhanced inactivity on the endothelium. We investigated endothelial properties before, during, and after 7 days of DI involving eight subjects. Microcirculatory functions were assessed with laser Doppler in the skin of the calf. We studied basal blood flow and endothelium-dependent and -independent vasodilation. We also measured plasma levels of microparticles, a sign of cellular dysfunction, and soluble endothelial factors, reflecting the endothelial state. Basal flow and endothelium-dependent vasodilation were reduced by DI (22 + or - 4 vs. 15 + or - 2 arbitrary units and 29 + or - 6% vs. 12 + or - 6%, respectively, P < 0.05), and this was accompanied by an increase in circulating endothelial microparticles (EMPs), which was significant on day 3 (42 + or - 8 vs. 65 + or - 10 EMPs/microl, P < 0.05), whereas microparticles from other cell origins remained unchanged. Plasma soluble VEGF decreased significantly during DI, whereas VEGF receptor 1 and soluble CD62E were unchanged, indicating that the increase in EMPs was associated with a change in antiapoptotic tone rather than endothelial activation. Our study showed that extreme physical inactivity in humans induced by 7 days of DI causes microvascular impairment with a disturbance of endothelial functions, associated with a selective increase in EMPs. Microcirculatory endothelial dysfunction might contribute to Cardiovascular Deconditioning as well as to hypodynamia-associated pathologies. In conclusion, the endothelium should be the focus of special care in situations of acute limitation of physical activity.
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Cardiovascular Deconditioning from autonomic nervous system to microvascular dysfunctions
Respiratory Physiology & Neurobiology, 2009Co-Authors: Mickael Coupe, Jacques-olivier Fortrat, C Gharib, I M Larina, Guillemette Gauquelinkoch, Marc-antoine CustaudAbstract:Weightlessness induces an acute syndrome called the Cardiovascular Deconditioning, associating orthostatic intolerance with syncope, increase in resting heart rate and decrease in physical capability. Orthostatic intolerance occurs after short term and long term head down bed rest and after long term space flight. Both head down bed rest and space flight induce a significant decrease of the spontaneous baroreflex sensitivity. However, spontaneous baroreflex sensitivity only characterizes the cardiac baroreflex loop. To go further with the analysis of Cardiovascular Deconditioning we were interested in the microcirculation. As the endothelium plays a crucial role in the regulation of vascular homeostasis and local blood flow, we hypothesized that endothelial dysfunction is associated with bed rest induced changes. We investigated endothelial properties before and after 56 days of bed rest in 8 women of control group and in 8 women who regularly performed physical exercise as countermeasure. Our study shows that prolonged bed rest causes impairment of endothelium-dependent functions at the microcirculation level, along with an increase in circulating endothelial cells. Endothelium should be a target for countermeasures during periods of prolonged bed rest or exposure to weightlessness.
Steven H Platts - One of the best experts on this subject based on the ideXlab platform.
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orthostatic intolerance after iss and space shuttle missions
Aerospace medicine and human performance, 2015Co-Authors: Alan H. Feiveson, Michael B Stenger, Sydney P Stein, Steven H PlattsAbstract:INTRODUCTION: Cardiovascular Deconditioning apparently progresses with flight duration, resulting in a greater incidence of orthostatic intolerance following long-duration missions. Therefore, we anticipated that the proportion of astronauts who could not complete an orthostatic tilt test (OTT) would be higher on landing day and the number of days to recover greater after International Space Station (ISS) than after Space Shuttle missions. METHODS: There were 20 ISS and 65 Shuttle astronauts who participated in 10-min 80° head-up tilt tests 10 d before launch, on landing day (R+0), and 3 d after landing (R+3). Fisher's Exact Test was used to compare the ability of ISS and Shuttle astronauts to complete the OTT. Cox regression was used to identify Cardiovascular parameters associated with OTT completion and mixed model analysis was used to compare the change and recovery rates between groups. RESULTS: The proportion of astronauts who completed the OTT on R+0 (2 of 6) was less in ISS than in Shuttle astronauts (52 of 65). On R+3, 13 of 15 and 19 of 19 of the ISS and Shuttle astronauts, respectively, completed the OTT. An index comprised of stroke volume and diastolic blood pressure provided a good prediction of OTT completion and was altered by spaceflight similarly for both astronaut groups, but recovery was slower in ISS than in Shuttle astronauts. CONCLUSIONS: The proportion of ISS astronauts who could not complete the OTT on R+0 was greater and the recovery rate slower after ISS compared to Shuttle missions. Thus, mission planners and crew surgeons should anticipate the need to tailor scheduled activities and level of medical support to accommodate protracted recovery after long-duration microgravity exposures.
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Artificial gravity training reduces bed rest-induced Cardiovascular Deconditioning
European Journal of Applied Physiology, 2012Co-Authors: Michael B Stenger, Stuart M. C. Lee, Tiffany R. Phillips, Alan D. Moore, Charles F. Knapp, William H. Paloski, Sondra A Perez, Joyce M Evans, Steven H PlattsAbstract:We studied 15 men (8 treatment, 7 control) before and after 21 days of 6º head-down tilt to determine whether daily, 1-h exposures to 1.0 G_z (at the heart) artificial gravity (AG) would prevent bed rest-induced Cardiovascular Deconditioning. Testing included echocardiographic analysis of cardiac function, plasma volume (PV), aerobic power ( V O_2pk) and Cardiovascular and neuroendocrine responses to 80º head-up tilt (HUT). Data collected during HUT were ECG, stroke volume (SV), blood pressure (BP) and blood for catecholamines and vasoactive hormones. Heart rate (HR), cardiac output (CO), total peripheral resistance, and spectral power of BP and HR were calculated. Bed rest decreased PV, supine and HUT SV, and indices of cardiac function in both groups. Although PV was decreased in control and AG after bed rest, AG attenuated the decrease in orthostatic tolerance [pre- to post-bed rest change; control: −11.8 ± 2.0, AG: −6.0 ± 2.8 min ( p = 0.012)] and V O_2pk [pre- to post-bed rest change; control: −0.39 ± 0.11, AG: −0.17 ± 0.06 L/min ( p = 0.041)]. AG prevented increases in pre-tilt levels of plasma renin activity [pre- to post-bed rest change; control: 1.53 ± 0.23, AG: −0.07 ± 0.34 ng/mL/h ( p = 0.001)] and angiotensin II [pre- to post-bed rest change; control: 3.00 ± 1.04, AG: −0.63 ± 0.81 pg/mL ( p = 0.009)] and increased HUT aldosterone [post-bed rest; control: 107 ± 30 pg/mL, AG: 229 ± 68 pg/mL ( p = 0.045)] and norepinephrine [post-bed rest; control: 453 ± 107, AG: 732 ± 131 pg/mL ( p = 0.003)]. We conclude that AG can mitigate some aspects of bed rest-induced Cardiovascular Deconditioning, including orthostatic intolerance and aerobic power. Mechanisms of improvement were not cardiac-mediated, but likely through improved sympathetic responsiveness to orthostatic stress.
J L Cuche - One of the best experts on this subject based on the ideXlab platform.
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norepinephrine kinetics in the rat with tail suspension induced central hypervolemia as a model of cardio vascular Deconditioning
Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology, 2000Co-Authors: Emmanuelle Maignan, M Safar, E Martel, J L CucheAbstract:Tail-suspension (TS) in the rat represents an interesting experimental condition to mimic, on Earth, the microgravity-induced Cardiovascular Deconditioning although the rat's profile of response is partially different from human's. To investigate underlying pathophysiological mechanisms, we have speculated on a decreased activity of the sympathetic system, (sigma S) triggered by the increase of the central venous pressure (CVP) induced by TS. Thus a decreased activity of the sigma S could account, at least partly, for the Deconditioning of the Cardiovascular system. The sympathetic activity (sigma A) was evaluated through measurement of the norepinephrine (NE) kinetics in rats that were tail-suspended for either 6, 24 or 48 hours. Neither NE spillover rate nor metabolic clearance rate were changed during TS, as compared to control. Thus, TS for a short period of time in the rat is unlikely to trigger a decrease of the sigma A.
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further study on the carotid baroreflex system in the Cardiovascular Deconditioning induced by head down tilt
Aviation Space and Environmental Medicine, 1998Co-Authors: B Pannier, M Slama, Alain P Guerin, E Martel, G London, M Safar, J L CucheAbstract:HYPOTHESIS The responses of the carotid baroreflex and of the peripheral sympathetic system to stimulations induced by either lower body negative pressure (LBNP -40 mmHg) or cold pressor test were investigated in eight volunteers before and after 48 h in the -6 degrees head-down tilt (HDT). METHODS Geometry (diastolic diameter and pulsatile distention) and dynamics (cross-sectional compliance and tangential tension) of the bulb and the common carotid artery were investigated using ultrasonic devices, echotracking and aplanation tonometry. The activity of the sympathetic system was evaluated through measurements of plasma concentrations of catecholamines (CAs) and 3,4-dihydroxyphenyl glycol (DHPG). RESULTS During LBNP -40 mmHg, the pulsed tangential tension was decreased and the pressure amplification, induced by the reflexion of the pressure wave, was increased with no difference between before and after HDT. Since cross-sectional compliance and distensibility coefficient remained unchanged and the carotid contour of the waveform unaltered, it is concluded that the carotid reflexogenic area reads the same message during LBNP whether the Cardiovascular system was deconditioned or not. Nonetheless, during LBNP after 48 h HDT, the heart rate accelerated faster and CAs and DHPG concentrations increased out of proportion, suggesting that the peripheral sympathetic activity was more reactive after HDT than before. Finally, forearm vascular resistances were measured in response to cold pressor test; they increased in the same proportion after HDT when compared with before. CONCLUSION Results indicate that the carotid baroreflex and the peripheral sympathetic system were not deficient after 48 h HDT.
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mechanisms of the Cardiovascular Deconditioning induced by tail suspension in the rat
American Journal of Physiology-heart and Circulatory Physiology, 1998Co-Authors: Eric Martel, Pascal Ponchon, Pascal Champeroux, Jeanluc Elghozi, Jeanfrancois Renaud De La Faverie, Hubert Dabire, Bruno Pannier, Serge Richard, Michel E Safar, J L CucheAbstract:The aim of the present work was to obtain insights into the pathophysiology of Cardiovascular Deconditioning (CVD) induced by tail suspension (TS) in the rat: during TS, when central venous pressur...
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Central hypervolemia in the conscious rat: a model of Cardiovascular Deconditioning.
Journal of Applied Physiology, 1996Co-Authors: Eric Martel, Michel E Safar, Champeroux P, Lacolley P, S. Richard, J L CucheAbstract:The aim of the present study as to investigate whether increased central hypervolemia induced by tail suspension (TS) in the rat is an appropriate model of Cardiovascular Deconditioning (CVD). First, the physiological relationship between central venous pressure (CVP) and extracellular fluid volume (ECFV) was studied. TS (20 degrees) increased CVP (5.8 +/- 0.7 vs. 2.8 +/- 0.8 mmHg; P < 0.01). After 24 h of TS, CVP had returned to control range while ECFV was reduced by 19%. CVP kinetics during 24 h of TS was not affected by either reduction (-20%) or augmentation (/35%) of the ECFV. The normalization of CVP is likely to be a consequence of ECFV reduction, which itself is reduced by increased urinary excretion of water and sodium. Second, recovery from TS was studied. Resumption of the horizontal position was shown to be associated with a significant increase of heart rate (HR) and a slight reduction of blood pressure (BP); there was an apparent delay between increased HR and reduced BP. This imbalance between HR and BP is compatible with CVD. A model of simulated orthostatism (SO) was developed to further investigate the responses of HR and BP. Interestingly, SO (90 degrees rotation) in the normal rat was associated with significant tachycardia and a slight increase of BP. This pattern remained stable for at least 3 h. In rats that were tail suspended for 48 h, episodes of hypotension and bradycardia (5 +/- 1 in 3 h) suggested a defect in adaptation to increased hydrostatic pressure. In conclusion, TS appears to be an appropriate model of CVD. Reduction process. Return to horizontal position in TS rats induced a tachycardia with minimal effects on BP; this pattern is close to that observed in humans assuming upright posture. SO in previously TS rats disclosed episodes of hypotension and bradycardia that deserve further investigation.
Giuseppe Baselli - One of the best experts on this subject based on the ideXlab platform.
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Identification of vascular responses to exercise and orthostatic stress in bed rest-induced Cardiovascular Deconditioning
2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009Co-Authors: Federico Aletti, Manuela Ferrario, Michela Cautero, Sergio Cerutti, Carlo Capelli, Giuseppe BaselliAbstract:In this paper, the effects of bed rest-induced Cardiovascular Deconditioning were investigated by means of a previously developed multivariate model for the assessment of arterial control of circulation. The vascular response to exercise and tilt, before and after a 14-day head down tilt bed rest, was identified and disentangled from the main mechanisms due to global, neural control of circulation. Results of the decomposition of diastolic pressure and pulse pressure beat-by-beat series and the relevant spectral analysis suggested that the autoregulation-related response is not affected by prolonged exposition to microgravity. As to the complex regulation of arterial blood pressure, a maintained responsiveness to sympathetic stimuli was found, even in presence of indications of the Cardiovascular Deconditioning, such as tachycardia, reset of baroreflex, cardiopulmonary unloading. These preliminary results emphasized the necessity for more complex analyses of the main alterations and compensatory mechanisms elicited by microgravity-induced-Cardiovascular Deconditioning, in order to develop more effective long term strategies to prevent it.
Joyce M Evans - One of the best experts on this subject based on the ideXlab platform.
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artificial gravity as a countermeasure to the Cardiovascular Deconditioning of spaceflight gender perspectives
Frontiers in Physiology, 2018Co-Authors: Joyce M Evans, Charles F. Knapp, Nandu GoswamiAbstract:Space flight-induced physiological Deconditioning resulting from decreased gravitational input, decreased plasma volume, and disruption of regulatory mechanisms is a significant problem in returning astronauts as well as in normal aging. Here we review effects of a promising countermeasure on Cardiovascular systems of healthy men and women undergoing Earth-based models of space-flight. This countermeasure is produced by a centrifuge and called artificial gravity (AG). Numerous studies have determined that AG improves orthostatic tolerance (as assessed by various protocols) of healthy ambulatory men, of men deconditioned by bed rest or by immersion (both wet and dry) and, in one case, following spaceflight. Although a few studies of healthy, ambulatory women and one study of women deconditioned by furosemide, have reported improvement of orthostatic tolerance following exposure to AG, studies of bed-rested women exposed to AG have not been conducted. However, in ambulatory, normovolemic subjects, AG training was more effective in men than women and more effective in subjects who exercised during AG than in those who passively rode the centrifuge. Acute exposure to an AG protocol, individualized to provide a common stimulus to each person, also improved orthostatic tolerance of normovolemic men and women and of furosemide-deconditioned men and women. Again, men's tolerance was more improved than women's. In both men and women, exposure to AG increased stroke volume, so greater improvement in men vs. women was due in part to their different vascular responses to AG. Following AG exposure, resting blood pressure (via decreased vascular resistance) decreased in men but not women, indicating an increase in men's vascular reserve. Finally, in addition to counteracting space flight Deconditioning, improved orthostatic tolerance through AG-induced improvement of stroke volume could benefit aging men and women on Earth.
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Artificial gravity training reduces bed rest-induced Cardiovascular Deconditioning
European Journal of Applied Physiology, 2012Co-Authors: Michael B Stenger, Stuart M. C. Lee, Tiffany R. Phillips, Alan D. Moore, Charles F. Knapp, William H. Paloski, Sondra A Perez, Joyce M Evans, Steven H PlattsAbstract:We studied 15 men (8 treatment, 7 control) before and after 21 days of 6º head-down tilt to determine whether daily, 1-h exposures to 1.0 G_z (at the heart) artificial gravity (AG) would prevent bed rest-induced Cardiovascular Deconditioning. Testing included echocardiographic analysis of cardiac function, plasma volume (PV), aerobic power ( V O_2pk) and Cardiovascular and neuroendocrine responses to 80º head-up tilt (HUT). Data collected during HUT were ECG, stroke volume (SV), blood pressure (BP) and blood for catecholamines and vasoactive hormones. Heart rate (HR), cardiac output (CO), total peripheral resistance, and spectral power of BP and HR were calculated. Bed rest decreased PV, supine and HUT SV, and indices of cardiac function in both groups. Although PV was decreased in control and AG after bed rest, AG attenuated the decrease in orthostatic tolerance [pre- to post-bed rest change; control: −11.8 ± 2.0, AG: −6.0 ± 2.8 min ( p = 0.012)] and V O_2pk [pre- to post-bed rest change; control: −0.39 ± 0.11, AG: −0.17 ± 0.06 L/min ( p = 0.041)]. AG prevented increases in pre-tilt levels of plasma renin activity [pre- to post-bed rest change; control: 1.53 ± 0.23, AG: −0.07 ± 0.34 ng/mL/h ( p = 0.001)] and angiotensin II [pre- to post-bed rest change; control: 3.00 ± 1.04, AG: −0.63 ± 0.81 pg/mL ( p = 0.009)] and increased HUT aldosterone [post-bed rest; control: 107 ± 30 pg/mL, AG: 229 ± 68 pg/mL ( p = 0.045)] and norepinephrine [post-bed rest; control: 453 ± 107, AG: 732 ± 131 pg/mL ( p = 0.003)]. We conclude that AG can mitigate some aspects of bed rest-induced Cardiovascular Deconditioning, including orthostatic intolerance and aerobic power. Mechanisms of improvement were not cardiac-mediated, but likely through improved sympathetic responsiveness to orthostatic stress.