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Robin A, Van Ombergen A, Laurens C, Bergouignan A, Vico L, Linossier MT, Pavy-Le Traon A, Kermorgant M, Chopard A, Py G, Green DA, Tipton M, Choukér A, Denise P, Normand H, Blanc S, Simon C, Rosnet E, Larcher F, Fernandez P, de Glisezinski I, Larrouy D, Harant-Farrugia I, Antunes I, Gauquelin-Koch G, Bareille MP, Billette De Villemeur R, Custaud MA, Navasiolava N. Comprehensive assessment of physiological responses in women during the ESA dry immersion VIVALDI microgravity simulation. Nat Commun 2023; 14:6311. [PMID: 37813884 PMCID: PMC10562467 DOI: 10.1038/s41467-023-41990-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/26/2023] [Indexed: 10/11/2023] Open
Abstract
Astronauts in microgravity experience multi-system deconditioning, impacting their inflight efficiency and inducing dysfunctions upon return to Earth gravity. To fill the sex gap of knowledge in the health impact of spaceflights, we simulate microgravity with a 5-day dry immersion in 18 healthy women (ClinicalTrials.gov Identifier: NCT05043974). Here we show that dry immersion rapidly induces a sedentarily-like metabolism shift mimicking the beginning of a metabolic syndrome with a drop in glucose tolerance, an increase in the atherogenic index of plasma, and an impaired lipid profile. Bone remodeling markers suggest a decreased bone formation coupled with an increased bone resorption. Fluid shifts and muscular unloading participate to a marked cardiovascular and sensorimotor deconditioning with decreased orthostatic tolerance, aerobic capacity, and postural balance. Collected datasets provide a comprehensive multi-systemic assessment of dry immersion effects in women and pave the way for future sex-based evaluations of countermeasures.
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Affiliation(s)
- Adrien Robin
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
| | | | - Claire Laurens
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Audrey Bergouignan
- Anschutz Health and Wellness Center, Division of Endocrinology, University of Colorado, Aurora, CO, USA
| | - Laurence Vico
- INSERM, University Jean Monnet, Mines Saint-Etienne, U 1059, Saint Etienne, France
| | | | - Anne Pavy-Le Traon
- Department of Neurology, CHU Toulouse and I2MC-INSERM 1297, Toulouse, France
| | - Marc Kermorgant
- Department of Neurology, CHU Toulouse and I2MC-INSERM 1297, Toulouse, France
| | - Angèle Chopard
- DMEM, Montpellier University, INRAE, Montpellier, France
| | - Guillaume Py
- DMEM, Montpellier University, INRAE, Montpellier, France
| | - David Andrew Green
- Centre of Human and Applied Physiological Sciences, King's College London, London, UK
| | - Michael Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, PO1 2EF, UK
| | - Alexander Choukér
- Laboratory of Translational Research Stress and Immunity, Department of Anesthesiology, Hospital of the Ludwig-Maximilians-University (LUM), Munich, Germany
| | - Pierre Denise
- Université de Caen Normandie, Inserm, COMETE U1075, CYCERON, CHU de Caen, F-14000, Caen, France
| | - Hervé Normand
- Université de Caen Normandie, Inserm, COMETE U1075, CYCERON, CHU de Caen, F-14000, Caen, France
| | - Stéphane Blanc
- DEPE-IPHC - Département Ecologie, Physiologie et Ethologie, Strasbourg, France
| | - Chantal Simon
- CarMeN Laboratory, INSERM 1060, INRA 1397, University Claude Bernard Lyon1, Human Nutrition Research Center Rhône-Alpes, Oullins, France
| | - Elisabeth Rosnet
- Faculty of Sport Sciences, Université de Reims Champagne-Ardenne, Reims, France
| | | | - Peter Fernandez
- INSERM, University Jean Monnet, Mines Saint-Etienne, U 1059, Saint Etienne, France
| | - Isabelle de Glisezinski
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Dominique Larrouy
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Isabelle Harant-Farrugia
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Inês Antunes
- Telespazio Belgium S.R.L. for the European Space Agency, Noordwijk, The Netherlands
| | | | | | | | - Marc-Antoine Custaud
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
| | - Nastassia Navasiolava
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
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Sadeghian F, Divsalar DN, Fadil R, Tavakolian K, Blaber AP. Canadian aging and inactivity study: Spaceflight-inspired exercises during head-down tilt bedrest blunted reductions in muscle-pump but not cardiac baroreflex in older persons. Front Physiol 2022; 13:943630. [PMID: 36213230 PMCID: PMC9532525 DOI: 10.3389/fphys.2022.943630] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/18/2022] [Indexed: 11/13/2022] Open
Abstract
As part of the first Canadian aging and inactivity study (CAIS) we assessed the efficacy of space-based exercise countermeasures for maintenance of cardiac and muscle-pump baroreflex in older persons during bedrest. An initiative of the Canadian Space Agency, Canadian Institutes of Health Research and the Canadian Frailty Network, CAIS involved 14 days of 6-degree head-down tilt bedrest (HDBR) with (Exercise) or without (Control) combined upper and lower body strength, aerobic, and high-intensity interval training exercise countermeasures. Twenty healthy men and women aged 55 to 65, randomly divided into control and exercise groups (male control (MC, n = 5), male exercise (ME, n = 5), female control (FC, n = 6), female exercise (FE, n = 4)) (age: 58.7 ± 0.5 years, height: 1.67 ± 0.02 m, body mass: 70.2 ± 3.2 kg; mean ± SEM), completed the study. Cardiac and muscle-pump baroreflex activity were assessed with supine-to-stand tests. Wavelet transform coherence was used to characterise cardiac and muscle-pump baroreflex fraction time active (FTA) and gain values, and convergent cross-mapping was used to investigate causal directionality between blood pressure (BP) and heart rate, as well as BP and lower leg muscle electromyography (EMG). Seven of the twenty participants were unable to stand for 6 minutes after HDBR, with six of those being female. Our findings showed that 2 weeks of bedrest impaired skeletal muscle’s ability to return blood to the venous circulation differently across various sexes and intervention groups. Comparing values after bed rest with before bed rest values, there was a significant increase in heart rates (∆ of +25%; +17% in MC to +33% in FC; p < 0.0001), beat-to-beat EMG decreased (∆ of −43%; −25% in ME to −58% in MC; p < 0.02), while BP change was dependent on sex and intervention groups. Unlike their male counterparts, in terms of muscle-pump baroreflex, female participants had considerably decreased FTA after HDBR (p < 0.01). All groups except female control demonstrated parallel decreases in cardiac active gain and causality, while the FC demonstrated an increase in cardiac causality despite a similar decline in cardiac active gain. Results showed that the proposed exercises may alleviate muscle-pump baroreflex declines but could not influence the cardiac baroreflex decline from 14 days of inactivity in older adults.
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Affiliation(s)
- Farshid Sadeghian
- Department of Biomedical Physiology and Kinesiology, Aerospace Physiology Laboratory, Simon Fraser University, Burnaby, Canada
| | - Donya Naz Divsalar
- Department of Biomedical Physiology and Kinesiology, Aerospace Physiology Laboratory, Simon Fraser University, Burnaby, Canada
| | - Rabie Fadil
- Biomedical Engineering Program, University of North Dakota, Grand Forks, ND, United States
| | - Kouhyar Tavakolian
- Biomedical Engineering Program, University of North Dakota, Grand Forks, ND, United States
| | - Andrew P. Blaber
- Department of Biomedical Physiology and Kinesiology, Aerospace Physiology Laboratory, Simon Fraser University, Burnaby, Canada
- Biomedical Engineering Program, University of North Dakota, Grand Forks, ND, United States
- *Correspondence: Andrew P. Blaber,
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Robin A, Wang L, Custaud MA, Liu J, Yuan M, Li Z, Lloret JC, Liu S, Dai X, Zhang J, Lv K, Li W, Gauquelin-Koch G, Wang H, Li K, Li X, Qu L, Navasiolava N, Li Y. Running vs. resistance exercise to counteract deconditioning induced by 90-day head-down bedrest. Front Physiol 2022; 13:902983. [PMID: 36117704 PMCID: PMC9473647 DOI: 10.3389/fphys.2022.902983] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
Spaceflight is associated with enhanced inactivity, resulting in muscular and cardiovascular deconditioning. Although physical exercise is commonly used as a countermeasure, separate applications of running and resistive exercise modalities have never been directly compared during long-term bedrest. This study aimed to compare the effectiveness of two exercise countermeasure programs, running and resistance training, applied separately, for counteracting cardiovascular deconditioning induced by 90-day head-down bedrest (HDBR). Maximal oxygen uptake (V˙O2max), orthostatic tolerance, continuous ECG and blood pressure (BP), body composition, and leg circumferences were measured in the control group (CON: n = 8), running exercise group (RUN: n = 7), and resistive exercise group (RES: n = 7). After HDBR, the decrease in V˙O2max was prevented by RUN countermeasure and limited by RES countermeasure (−26% in CON p < 0.05, −15% in RES p < 0.05, and −4% in RUN ns). Subjects demonstrated surprisingly modest orthostatic tolerance decrease for different groups, including controls. Lean mass loss was limited by RES and RUN protocols (−10% in CON vs. −5% to 6% in RES and RUN). Both countermeasures prevented the loss in thigh circumference (−7% in CON p < 0.05, −2% in RES ns, and −0.6% in RUN ns) and limited loss in calf circumference (−10% in CON vs. −7% in RES vs. −5% in RUN). Day–night variations in systolic BP were preserved during HDBR. Decrease in V˙O2max positively correlated with decrease in thigh (r = 0.54 and p = 0.009) and calf (r = 0.52 and p = 0.012) circumferences. During this 90-day strict HDBR, running exercise successfully preserved V˙O2max, and resistance exercise limited its decline. Both countermeasures limited loss in global lean mass and leg circumferences. The V˙O2max reduction seems to be conditioned more by muscular than by cardiovascular parameters.
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Affiliation(s)
- Adrien Robin
- Univ Angers, CHU Angers, CRC, INSERM, CNRS, MITOVASC, Equipe CarMe, SFR ICAT, Angers, France
| | - Linjie Wang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Marc-Antoine Custaud
- Univ Angers, CHU Angers, CRC, INSERM, CNRS, MITOVASC, Equipe CarMe, SFR ICAT, Angers, France
| | - Jiexin Liu
- Beijing Tiantan Hospital, Medical Capital University, Beijing, China
| | - Min Yuan
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Zhili Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | | | - Shujuan Liu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Xiaoqian Dai
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Jianfeng Zhang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Ke Lv
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Wenjiong Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | | | - Huijuan Wang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Kai Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Xiaotao Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Lina Qu
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Nastassia Navasiolava
- Univ Angers, CHU Angers, CRC, INSERM, CNRS, MITOVASC, Equipe CarMe, SFR ICAT, Angers, France
- *Correspondence: Nastassia Navasiolava, ; Yinghui Li,
| | - Yinghui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
- *Correspondence: Nastassia Navasiolava, ; Yinghui Li,
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Hedge ET, Patterson CA, Mastrandrea CJ, Sonjak V, Hajj-Boutros G, Faust A, Morais JA, Hughson RL. Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA). Front Physiol 2022; 13:928313. [PMID: 36017336 PMCID: PMC9395735 DOI: 10.3389/fphys.2022.928313] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 12/18/2022] Open
Abstract
Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults.
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Affiliation(s)
- Eric T. Hedge
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | | | | | - Vita Sonjak
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Guy Hajj-Boutros
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Andréa Faust
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - José A. Morais
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
- Division of Geriatric Medicine, McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Richard L. Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada
- *Correspondence: Richard L. Hughson,
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Advantages and Limitations of Current Microgravity Platforms for Space Biology Research. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app11010068] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human Space exploration has created new challenges and new opportunities for science. Reaching beyond the Earth’s surface has raised the issue of the importance of gravity for the development and the physiology of biological systems, while giving scientists the tools to study the mechanisms of response and adaptation to the microgravity environment. As life has evolved under the constant influence of gravity, gravity affects biological systems at a very fundamental level. Owing to limited access to spaceflight platforms, scientists rely heavily on on-ground facilities that reproduce, to a different extent, microgravity or its effects. However, the technical constraints of counterbalancing the gravitational force on Earth add complexity to data interpretation. In-flight experiments are also not without their challenges, including additional stressors, such as cosmic radiation and lack of convection. It is thus extremely important in Space biology to design experiments in a way that maximizes the scientific return and takes into consideration all the variables of the chosen setup, both on-ground or on orbit. This review provides a critical analysis of current ground-based and spaceflight facilities. In particular, the focus was given to experimental design to offer the reader the tools to select the appropriate setup and to appropriately interpret the results.
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Cardio-postural interactions and muscle-pump baroreflex are severely impacted by 60-day bedrest immobilization. Sci Rep 2020; 10:12042. [PMID: 32694819 PMCID: PMC7374578 DOI: 10.1038/s41598-020-68962-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 06/26/2020] [Indexed: 02/07/2023] Open
Abstract
To understand fundamental mechanisms associated with post-flight orthostatic intolerance we investigated the interaction between the cardiovascular and postural functions before and after 60 days of head down bedrest (HDBR). Twenty healthy young males (35.0 ± 1.7 years) were subjected to 60-day HDBR at 6˚ to simulate spaceflight-induced fluid shifts. A supine-to-stand (STS) test was conducted to evaluate cardio-postural control before and after (R) HDBR while an assessment of cardiovascular function was performed during HDBR. Beat-to-beat heart period, systolic blood pressure, and electromyography impulses were derived for wavelet transform coherence and causality analyses of the cardio-postural control and used to assess changes in the muscle-pump baroreflex. During quiet stand of the STS test, compared to baseline, heart rate was 50% higher on the day of exit from bedrest (R0) and 20% higher eight days later (R8). There was a 50% increase in deoxygenated hemoglobin on R0 and R8. Leg muscle activity reduced, and postural sway increased after HDBR. Causality of the muscle-pump baroreflex was reduced on R0 (0.73 ± 0.2) compared to baseline (0.87 ± 0.2) with complete recovery by R8. The muscle-pump baroreflex also had decreased gain and fraction time active following HDBR. Overall, our data show a significantly impaired muscle-pump baroreflex following bedrest.
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Goswami N, Blaber AP, Hinghofer-Szalkay H, Montani JP. Orthostatic Intolerance in Older Persons: Etiology and Countermeasures. Front Physiol 2017; 8:803. [PMID: 29163185 PMCID: PMC5677785 DOI: 10.3389/fphys.2017.00803] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 09/29/2017] [Indexed: 12/16/2022] Open
Abstract
Orthostatic challenge produced by upright posture may lead to syncope if the cardiovascular system is unable to maintain adequate brain perfusion. This review outlines orthostatic intolerance related to the aging process, long-term bedrest confinement, drugs, and disease. Aging-associated illness or injury due to falls often leads to hospitalization. Older patients spend up to 83% of hospital admission lying in bed and thus the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population. This review examines current scientific knowledge regarding orthostatic intolerance and how it comes about and provides a framework for understanding of (patho-) physiological concepts of cardiovascular (in-) stability in ambulatory and bedrest confined senior citizens as well as in individuals with disease conditions [e.g., orthostatic intolerance in patients with diabetes mellitus, multiple sclerosis, Parkinson's, spinal cord injury (SCI)] or those on multiple medications (polypharmacy). Understanding these aspects, along with cardio-postural interactions, is particularly important as blood pressure destabilization leading to orthostatic intolerance affects 3-4% of the general population, and in 4 out of 10 cases the exact cause remains elusive. Reviewed also are countermeasures to orthostatic intolerance such as exercise, water drinking, mental arithmetic, cognitive training, and respiration training in SCI patients. We speculate that optimally applied countermeasures such as mental challenge maintain sympathetic activity, and improve venous return, stroke volume, and consequently, blood pressure during upright standing. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement or bedrest is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons.
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Affiliation(s)
- Nandu Goswami
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Andrew P Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Helmut Hinghofer-Szalkay
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Jean-Pierre Montani
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland
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Orthostatic Intolerance Is Independent of the Degree of Autonomic Cardiovascular Adaptation after 60 Days of Head-Down Bed Rest. BIOMED RESEARCH INTERNATIONAL 2015; 2015:896372. [PMID: 26425559 PMCID: PMC4573436 DOI: 10.1155/2015/896372] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 08/12/2015] [Accepted: 08/19/2015] [Indexed: 11/17/2022]
Abstract
Spaceflight and head-down bed rest (HDBR) can induce the orthostatic intolerance (OI); the mechanisms remain to be clarified. The aim of this study was to determine whether or not OI after HDBR relates to the degree of autonomic cardiovascular adaptation. Fourteen volunteers were enrolled for 60 days of HDBR. A head-up tilt test (HUTT) was performed before and after HDBR. Our data revealed that, in all nonfainters, there was a progressive increase in heart rate over the course of HDBR, which remained higher until 12 days of recovery. The mean arterial pressure gradually increased until day 56 of HDBR and returned to baseline after 12 days of recovery. Respiratory sinus arrhythmia and baroreflex sensitivity decreased during HDBR and remained suppressed until 12 days of recovery. Low-frequency power of systolic arterial pressure increased during HDBR and remained elevated during recovery. Three subjects fainted during the HUTT after HDBR, in which systemic vascular resistance did not increase and remained lower until syncope. None of the circulatory patterns significantly differed between the fainters and the nonfainters at any time point. In conclusion, our data indicate that the impaired orthostatic tolerance after HDBR could not be distinguished by estimation of normal hemodynamic and/or neurocardiac data.
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Effects of gravitational acceleration on cardiovascular autonomic control in resting humans. Eur J Appl Physiol 2015; 115:1417-27. [DOI: 10.1007/s00421-015-3117-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 01/26/2015] [Indexed: 10/24/2022]
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Marušič U, Meeusen R, Pišot R, Kavcic V. The brain in micro- and hypergravity: the effects of changing gravity on the brain electrocortical activity. Eur J Sport Sci 2014; 14:813-22. [PMID: 24734884 DOI: 10.1080/17461391.2014.908959] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Understanding the effects of increased and decreased gravity on central nervous system is essential for developing proper physical and cognitive countermeasures to assure safe and effective space missions and human survival in space. This short review covers the available literature on the brain electrocortical activity effects of decreased and increased gravitational force comparing to the 1g Earth conditions. Among all neuroimaging methods such as functional magnetic resonance imaging (fMRI), positron-emission tomography (PET), diffusion tensor imaging (DTI), the electroencephalography (EEG) was found to be suitable method to monitor brain electrocortical activity in the extreme environments. Due to complexity and high cost of space flight missions, ground-based models have been employed to simulate microgravity effects on human body. Surprisingly, there is very limited number of publications reporting gravity-dependent EEG spectral changes. With increased gravity there are initially increased EEG activity in higher frequencies and at around 4 g appears loss of consciousness with accompanying slowing of EEG due to hypoxia. In microgravity, the most prevalent changes in EEG are faster frequencies such as alpha and beta. The results from simulated microgravity (bed rest) are pointing to changes in theta and alpha, representing signs of cortical inhibition. The changes in EEG activity in space flight are attributed to a decreased sensorimotor input while in parabolic flights short and fast transitions from hyper to microgravity presumably reflect lower arousal levels and emotional processes in microgravity. Thus, based on limited research about gravity-related changes in EEG from different environments it is difficult to draw any unequivocal conclusions. Additional systematic studies about electrocortical activity in space and parabolic flights, as well as longer bed rest studies are needed in order to advance knowledge about brain functioning in extreme conditions such as space flights.
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Affiliation(s)
- Uroš Marušič
- a Science and Research Centre, Institute for Kinesiology Research , University of Primorska , Koper , Slovenia
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Liang X, Zhang L, Shen H, Chen X, Wan Y, Li L, Liang Y, Yu X, Guo Y, Yu J, Shu W, Tan C, Lv K, Xiao Y, Chen X, Chen S, Guo J. Effects of a 45-day head-down bed rest on the diurnal rhythms of activity, sleep, and heart rate. BIOL RHYTHM RES 2014. [DOI: 10.1080/09291016.2014.882093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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12
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Adami A, Pizzinelli P, Bringard A, Capelli C, Malacarne M, Lucini D, Simunič B, Pišot R, Ferretti G. Cardiovascular re-adjustments and baroreflex response during clinical reambulation procedure at the end of 35-day bed rest in humans. Appl Physiol Nutr Metab 2013; 38:673-80. [DOI: 10.1139/apnm-2012-0396] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the reambulation procedure after 35-day head-down tilt bed rest (HDTBR) for 9 men, we recorded for the first time heart rate (HR; with electrocardiogram) and arterial pressure profiles (fingertip plethysmography) for 5 min in HDTBR and horizontal (SUP) positions, followed by 12 min in standing position, during which 4 subjects fainted (intolerant, INT) and were laid horizontal again (Recovery). We computed: mean arterial pressure (P¯; pressure profiles integral mean), stroke volume (SV; obtained with Modelflow method), and cardiac output (Q̇; SV × HR). All cardiovascular data remained stable in HDTBR and SUP for both groups (EXP). Taking the upright posture, EXP showed a decrease in SV and an increase in HR, becoming significantly different from SUP within 1 min. Further evolution of these parameters kept Q̇ stable in both groups until the second minute of standing. Afterward, in INT, P̄ precipitated without further HR increases: SV stopped being corrected and Q̇ reached 2.9 ± 0.4 L·min−1 at the last 15 s of standing. Sudden drop in P̄ allowed identification of a low-pressure threshold in INT (70.7 ± 12.9 mm Hg), after which syncope occurred within 80 s. During Recovery, baroreflex curves showed a flat phase (P̄ increase, HR stable), followed by a steep phase (P̄ increased, HR decreased, starting when P̄ was 84.5 ± 12.5 mm Hg and Q̇ was 9.6 ± 1.5 L·min−1). INT, in contrast with tolerant subjects, did not sustain standing because HR was unable to correct for the P̄ drop. These results indicate a major role for impaired arterial baroreflexes in the onset of orthostatic intolerance.
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Affiliation(s)
- Alessandra Adami
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
| | - Paolo Pizzinelli
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Aurélien Bringard
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
| | - Carlo Capelli
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e Motorie, Facoltà di Scienze Motorie, Università di Verona, via F. Casorati, 54, 37100 Verona, Italia
| | - Mara Malacarne
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Daniela Lucini
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Boštjan Simunič
- Institute of Kinesiology Research, Science and Research Center, University of Primorska, Koper, Garibaldijeva street 1, 6000 Koper, Slovenia
| | - Rado Pišot
- Institute of Kinesiology Research, Science and Research Center, University of Primorska, Koper, Garibaldijeva street 1, 6000 Koper, Slovenia
| | - Guido Ferretti
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
- Dipartimento di Scienze Biomediche e Biotecnologie, Facoltà di Medicina, Università di Brescia, Viale Europa 11, 25123 Brescia, Italia
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Liang X, Zhang L, Wan Y, Yu X, Guo Y, Chen X, Tan C, Huang T, Shen H, Chen X, Li H, Lv K, Sun F, Chen S, Guo J. Changes in the diurnal rhythms during a 45-day head-down bed rest. PLoS One 2012; 7:e47984. [PMID: 23110150 PMCID: PMC3480480 DOI: 10.1371/journal.pone.0047984] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/19/2012] [Indexed: 01/20/2023] Open
Abstract
In spaceflight human circadian rhythms and sleep patterns are likely subject to change, which consequently disturbs human physiology, cognitive abilities and performance efficiency. However, the influence of microgravity on sleep and circadian clock as well as the underlying mechanisms remain largely unknown. Placing volunteers in a prone position, whereby their heads rest at an angle of -6° below horizontal, mimics the microgravity environment in orbital flight. Such positioning is termed head-down bed rest (HDBR). In this work, we analysed the influence of a 45-day HDBR on physiological diurnal rhythms. We examined urinary electrolyte and hormone excretion, and the results show a dramatic elevation of cortisol levels during HDBR and recovery. Increased diuresis, melatonin and testosterone were observed at certain periods during HDBR. In addition, we investigated the changes in urination and defecation frequencies and found that the rhythmicity of urinary frequency during lights-off during and after HDBR was higher than control. The grouped defecation frequency data exhibits rhythmicity before and during HDBR but not after HDBR. Together, these data demonstrate that HDBR can alter a number of physiological processes associated with diurnal rhythms.
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Affiliation(s)
- Xiaodi Liang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Lin Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yufeng Wan
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xinyang Yu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yiming Guo
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiaoping Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing, China
| | - Cheng Tan
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing, China
| | - Tianle Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Hanjie Shen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xianyun Chen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Hongying Li
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ke Lv
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing, China
| | - Fei Sun
- School of Life Sciences, University of Science and Technology of China, and Hefei National Laboratory for Physical Sciences at Microscale, Hefei, China
| | - Shanguang Chen
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing, China
| | - Jinhu Guo
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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14
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Oxygen deficits and oxygen delivery kinetics during submaximal intensity exercise in humans after 14 days of head-down tilt-bed rest. Eur J Appl Physiol 2009; 107:51-9. [DOI: 10.1007/s00421-009-1098-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2009] [Indexed: 12/20/2022]
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15
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Kölegård R, Mekjavic IB, Eiken O. Increased distensibility in dependent veins following prolonged bedrest. Eur J Appl Physiol 2009; 106:547-54. [DOI: 10.1007/s00421-009-1044-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2009] [Indexed: 10/20/2022]
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16
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Eiken O, Kölegård R, Mekjavic IB. Pressure-distension relationship in arteries and arterioles in response to 5 wk of horizontal bedrest. Am J Physiol Heart Circ Physiol 2008; 295:H1296-H1302. [DOI: 10.1152/ajpheart.00576.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that exposure to prolonged recumbency (bedrest), and thus reductions of intravascular pressure gradients, increases pressure distension in arteries/arterioles in the legs. Ten subjects underwent 5 wk of horizontal bedrest. Pressure distension was investigated in arteries and arterioles before and after the bedrest, with the subject seated or supine in a hyperbaric chamber with either one arm or a lower leg protruding through a hole in the chamber door. Increased pressure in the vessels of the arm/leg was accomplished by increasing chamber pressure. Vessel diameter and flow were measured in the brachial and posterior tibial arteries using Doppler ultrasonography. Electrical tissue impedance was measured in the test limb. Bedrest increased ( P < 0.01) pressure distension threefold in the tibial artery (from 8 ± 7% to 24 ± 11%) and by a third ( P < 0.05) in the brachial artery (from 15 ± 9% to 20 ± 10%). The pressure-induced increase in tibial artery flow was more pronounced ( P < 0.01) after (50 ± 39 ml/min) than before (13 ± 23 ml/min) bedrest, whereas the brachial artery flow response was unaffected by bedrest. The pressure-induced decrease in tissue impedance in the leg was more pronounced ( P < 0.01) after (16 ± 7%) than before (10 ± 6%) bedrest, whereas bedrest did not affect the impedance response in the arm. Thus, withdrawal of the hydrostatic pressure gradients that act along the blood vessels in erect posture markedly increases pressure distension in dependent arteries and arterioles.
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17
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Pavy-Le Traon A, Heer M, Narici MV, Rittweger J, Vernikos J. From space to Earth: advances in human physiology from 20 years of bed rest studies (1986-2006). Eur J Appl Physiol 2007; 101:143-94. [PMID: 17661073 DOI: 10.1007/s00421-007-0474-z] [Citation(s) in RCA: 375] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2007] [Indexed: 01/11/2023]
Abstract
Bed rest studies of the past 20 years are reviewed. Head-down bed rest (HDBR) has proved its usefulness as a reliable simulation model for the most physiological effects of spaceflight. As well as continuing to search for better understanding of the physiological changes induced, these studies focused mostly on identifying effective countermeasures with encouraging but limited success. HDBR is characterised by immobilization, inactivity, confinement and elimination of Gz gravitational stimuli, such as posture change and direction, which affect body sensors and responses. These induce upward fluid shift, unloading the body's upright weight, absence of work against gravity, reduced energy requirements and reduction in overall sensory stimulation. The upward fluid shift by acting on central volume receptors induces a 10-15% reduction in plasma volume which leads to a now well-documented set of cardiovascular changes including changes in cardiac performance and baroreflex sensitivity that are identical to those in space. Calcium excretion is increased from the beginning of bed rest leading to a sustained negative calcium balance. Calcium absorption is reduced. Body weight, muscle mass, muscle strength is reduced, as is the resistance of muscle to insulin. Bone density, stiffness of bones of the lower limbs and spinal cord and bone architecture are altered. Circadian rhythms may shift and are dampened. Ways to improve the process of evaluating countermeasures--exercise (aerobic, resistive, vibration), nutritional and pharmacological--are proposed. Artificial gravity requires systematic evaluation. This review points to clinical applications of BR research revealing the crucial role of gravity to health.
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Affiliation(s)
- A Pavy-Le Traon
- Service D'explorations Fonctionnelles Respiratoires Et d'analyses Physiologiques, Hopital La Cavale Blanche, University Hospital of Brest, 29609, Brest Cedex, France.
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18
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Abstract
Body fluid regulation is affected by gravity. The primary mechanisms of the etiology of hypovolemia found in simulation studies on earth and after space flight are different. The increased diuresis after increase of central blood volume postulated by Henry Gauer could not be found. Based on recent findings, new hypotheses about fluid volume regulation during space flight have emerged. The reduced blood volume in space is the result of 1) a negative balance of decreased fluid intake and smaller reduction of urine output; 2) fast fluid shifts from the intravascular to interstitial space as the result of lower transmural pressure after reduced compression of all tissue by gravitational forces especially of the thorax cage; and 3) fluid shifts from intravascular to muscle interstitial space because of less muscle tone required to maintain body posture. Additionally, loss of erythrocytes reduces blood volume. The attenuated diuresis during space flight can be explained by increased retention after stress-mediated sympathetic activation during initial phase of space flight, stimulation caused by reduced red cell mass, and activation after fast blood volume contraction. Additionally, the relation between plasma osmolarity and vasopressin release might be disturbed in microgravity.
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Affiliation(s)
- André Diedrich
- Center for Space Medicine and Physiology, Vanderbilt University School of Medicine, Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Nashville, Tennessee 37232-2195, USA.
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19
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Linnarsson D, Spaak J, Sundblad P. Baroreflex impairment during rapid posture changes at rest and exercise after 120 days of bed rest. Eur J Appl Physiol 2005; 96:37-45. [PMID: 16235067 DOI: 10.1007/s00421-005-0062-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2005] [Indexed: 10/25/2022]
Abstract
Orthostatic intolerance is common after space flight and head-down tilt (HDT) bed rest. We hypothesized that HDT-induced impairments of arterial blood pressure (AP) control would be more marked during exercise and that recovery of baroreflex function after very long-term HDT would be delayed. Six subjects were studied before (BDC) during (day 60, D60; D113) and after (recovery day 0, R0; R3; R15) 120 days of HDT. Supine resting subjects were exposed to repeated 1 min passive tilts to upright at 3-min interval. During 50 W steady-state exercise corresponding tilt had a 2-min duration at 4-min interval. The amplitudes of the tilt-induced transient beat-by-beat deviations in AP and rate (HR) were determined during the gravity transients. At rest these deviations did not change over time, but during exercise the total peak-to-nadir range of deviations in systolic AP (SAP) at up-tilt and down-tilt increased to 168+/-16% (mean+/-SEM) of BDC at D113 with no clear recovery upto and including R15. Counter-regulatory HR responses were not increased proportionally and especially not tachycardic responses to up-tilt, resulting in a reduction of baroreflex sensitivity (deltaRR-interval/deltaSAP) by 55+/-9% of BDC at D113 with no recovery upto and including R15. We conclude that prolonged bed rest cause long-lasting impairments in AP control and baroreflex function in exercising humans.
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Affiliation(s)
- D Linnarsson
- Section of Environmental Physiology, Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden.
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20
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Grenon SM, Hurwitz S, Sheynberg N, Xiao X, Ramsdell CD, Mai CL, Kim C, Cohen RJ, Williams GH. Role of individual predisposition in orthostatic intolerance before and after simulated microgravity. J Appl Physiol (1985) 2004; 96:1714-22. [PMID: 15075309 DOI: 10.1152/japplphysiol.01274.2003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Orthostatic intolerance (OI) is a major problem after spaceflight. Its etiology remains uncertain, but reports have pointed toward an individual susceptibility to OI. We hypothesized that individual predisposition plays an important role in post-bed rest OI. Twenty-four healthy male subjects were equilibrated on a constant diet, after which they underwent tilt-stand test (pre-TST). They then completed 14-16 days of head-down-tilt bed rest, and 14 of the subjects underwent repeat tilt-stand test (post-TST). During various phases, the following were performed: 24-h urine collections and hormonal measurements, plethysmography, and cardiovascular system identification (a noninvasive method to assess autonomic function and separately quantify parasympathetic and sympathetic responsiveness). Development of presyncope or syncope defined OI. During pre-TST, 11 subjects were intolerant and 13 were tolerant. At baseline, intolerant subjects had lower serum aldosterone (P < 0.01), higher excretion of potassium (P = 0.01), lower leg venous compliance (P = 0.03), higher supine parasympathetic responsiveness (P = 0.02), and lower standing sympathetic responsiveness (P = 0.048). Of the 14 subjects who completed post-TST, 9 were intolerant and 5 were tolerant. Intolerant subjects had lower baseline serum cortisol (P = 0.03) and a higher sodium level (P = 0.02) compared with tolerant subjects. Thus several physiological characteristics were associated with increased susceptibility to OI. We propose a new model for OI, whereby individuals with greater leg venous compliance recruit compensatory mechanisms (activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, and withdrawal of the parasympathetic nervous system) in the face of daily postural challenges, which places them at an advantage to face orthostatic stress. With head-down-tilt bed rest, the stimulus to recruit compensatory mechanisms disappears, and differences between the two subgroups attenuate.
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Affiliation(s)
- S M Grenon
- Division of Endocrinology, Hypertension and Diabetes, Brigham and Women's Hospital, Boston, MA 02115, USA
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21
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Belin de Chantemèle E, Pascaud L, Custaud MA, Capri A, Louisy F, Ferretti G, Gharib C, Arbeille P. Calf venous volume during stand-test after a 90-day bed-rest study with or without exercise countermeasure. J Physiol 2004; 561:611-22. [PMID: 15331681 PMCID: PMC1665364 DOI: 10.1113/jphysiol.2004.069468] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The objectives to determine both the contribution to orthostatic intolerance (OI) of calf venous volume during a stand-test, and the effects of a combined eccentric-concentric resistance exercise countermeasure on both vein response to orthostatic test and OI, after 90-day head-down tilt bed-rest (HDT). The subjects consisted of a control group (Co-gr, n = 9) and an exercise countermeasure group (CM-gr, n = 9). Calf volume and vein cross-sectional area (CSA) were assessed by plethysmography and echography during pre- and post-HDT stand-tests. From supine to standing (post-HDT), the tibial and gastrocnemius vein CSA increased significantly in intolerant subjects (tibial vein, +122% from pre-HDT; gastrocnemius veins, +145%; P < 0.05) whereas it did not in tolerant subjects. Intolerant subjects tended to have a higher increase in calf filling volume than tolerant subjects, in both sitting and standing positions. The countermeasure did not reduce OI. Absolute calf volume decreased similarly in both groups. Tibial and gastrocnemius vein CSA at rest did not change during HDT in either group. During the post-HDT stand-test, the calf filling volume increased more in the CM-gr than in the Co-gr both in the sitting (+1.3 +/- 5.1%, vs. -7.3 +/- 4.3%; P < 0.05) and the standing positions (+56.1 +/- 23.7% vs. +1.6 +/- 9.6%; P < 0.05). The volume ejected by the muscle venous pump increased only in the CM-gr (+38.3 +/- 21.8%). This study showed that intolerant subjects had a higher increase in vein CSA in the standing position and a tendency to present a higher calf filling volume in the sitting and standing positions. It also showed that a combined eccentric-concentric resistance exercise countermeasure had no effects on either post-HDT OI or on the venous parameters related to it.
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Affiliation(s)
- Eric Belin de Chantemèle
- Laboratoire de Physiologie de l'Environnement, Faculté de Médecine Lyon Grange-Blanche, Lyon, France
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22
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Xiao X, Mukkamala R, Sheynberg N, Grenon SM, Ehrman MD, Mullen TJ, Ramsdell CD, Williams GH, Cohen RJ. Effects of simulated microgravity on closed-loop cardiovascular regulation and orthostatic intolerance: analysis by means of system identification. J Appl Physiol (1985) 2004; 96:489-97. [PMID: 14514703 DOI: 10.1152/japplphysiol.00602.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Microgravity-induced orthostatic intolerance (OI) continues to be a primary concern for the human space program. To test the hypothesis that exposure to simulated microgravity significantly alters autonomic nervous control and, thus, contributes to increased incidence of OI, we employed the cardiovascular system identification (CSI) technique to evaluate quantitatively parasympathetic and sympathetic regulation of heart rate (HR). The CSI method analyzes second-to-second fluctuations in noninvasively measured HR, arterial blood pressure, and instantaneous lung volume. The coupling mechanisms between these signals are characterized by using a closed-loop model. Parameters reflecting parasympathetic and sympathetic responsiveness with regard to HR regulation can be extracted from the identified coupling mechanisms. We analyzed data collected from 29 human subjects before and after 16 days of head-down-tilt bed rest (simulated microgravity). Statistical analyses showed that parasympathetic and sympathetic responsiveness was impaired by bed rest. A lower sympathetic responsiveness and a higher parasympathetic responsiveness measured before bed rest identified individuals at greater risk of OI before and after bed rest. We propose an algorithm to predict OI after bed rest from measures obtained before bed rest.
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Affiliation(s)
- Xinshu Xiao
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
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23
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Serrador JM, Shoemaker JK, Brown TE, Kassam MS, Bondar RL, Schlegel TT. Cerebral vasoconstriction precedes orthostatic intolerance after parabolic flight. Brain Res Bull 2000; 53:113-20. [PMID: 11033215 DOI: 10.1016/s0361-9230(00)00315-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effects of brief but repeated bouts of micro- and hypergravity on cerebrovascular responses to head-up tilt (HUT) were examined in 13 individuals after (compared to before) parabolic flight. Middle cerebral artery mean flow velocity (MCA MFV; transcranial Doppler ultrasound), eye level blood pressure (BP) and end tidal CO(2) (P(ET)CO(2)) were measured while supine and during 80 degrees HUT for 30 min or until presyncope. In the postflight tests subjects were classified as being orthostatically tolerant (OT) (n = 7) or intolerant (OI) (n = 6). BP was diminished with HUT in the OT group in both tests (p < 0.05) whereas postflight BP was not different from supine in the OI group. Postflight compared to preflight, the reduction in P(ET)CO(2) with HUT (p < 0.05) increased in both groups, although significantly so only in the OI group (p < 0.05). The OI group also had a significant decrease in supine MCA MFV postflight (p < 0.05) that was unaccompanied by a change in supine P(ET)CO(2). The decrease in MCA MFV that occurred during HUT in both groups preflight (p < 0.05) was accentuated only in the OI group postflight, particularly during the final 30 s of HUT (p < 0.05). However, this accentuated decrease in MCA MFV was not correlated to the greater decrease in P(ET)CO(2) during the same period (R = 0.20, p = 0.42). Although cerebral vascular resistance (CVR) also increased in the OI group during the last 30 s of HUT postflight (p < 0.05), the dynamic autoregulatory gain was not simultaneously changed. Therefore, we conclude that in the OI individuals, parabolic flight was associated with cerebral hypoperfusion following a paradoxical augmentation of CVR by a mechanism that was not related to changes in autoregulation nor strictly to changes in P(ET)CO(2).
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Affiliation(s)
- J M Serrador
- Neurovascular Research Lab, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
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Reybrouck T, Heidbüchel H, Van de Werf F, Ector H. Tilt training: a treatment for malignant and recurrent neurocardiogenic syncope. Pacing Clin Electrophysiol 2000; 23:493-8. [PMID: 10793440 DOI: 10.1111/j.1540-8159.2000.tb00833.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The treatment of neurocardiogenic syncope is insufficient in many cases. We hypothesized that the repeated exposure of the cardiovascular system to orthostatic stress could have a therapeutic effect on the regulation of cardiovascular reflex mechanisms. We have started a program of tilt training for heavily symptomatic patients. After hospital admission, patients were tilted daily (60-degree inclination), until syncope, or until a maximum of 45-90 minutes. The patients were instructed to continue a program of daily tilt training at home: two 30-minute sessions of upright standing against a vertical wall. No medication was prescribed. A total of 260 tilt table sessions were performed in 42 patients. The first tilt test was positive after 21 +/- 13 minutes. The syncope was cardioinhibitory in 14 cases, vasodepressor in 19, mixed in 9. At the time of hospital discharge, 41 patients could support 45 minutes of head-up tilting. After a mean follow-up time of 15.1 (SD 7.8) months, 36 patients remained completely free of syncope. Syncope still occurred in one patient and presyncope in four patients. One patient died from an extensive myocardial infarction. The abnormal autonomic reflex activity of neurocardiogenic syncope can be remedied by a program of continued tilt training without the administration of drugs. This new treatment has proven to be effective for the vasodepressor and the cardioinhibitory type of syncope.
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Affiliation(s)
- T Reybrouck
- Department of Cardiology, University Hospital Gasthuisberg, Leuven, Belgium
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25
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Shoemaker JK, Hogeman CS, Sinoway LI. Contributions of MSNA and stroke volume to orthostatic intolerance following bed rest. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R1084-90. [PMID: 10516248 DOI: 10.1152/ajpregu.1999.277.4.r1084] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined whether the altered orthostatic tolerance following 14 days of head-down tilt bed rest (HDBR) was related to inadequate sympathetic outflow or to excessive reductions in cardiac output during a 10- to 15-min head-up tilt (HUT) test. Heart rate, blood pressure (BP, Finapres), muscle sympathetic nerve activity (MSNA, microneurography), and stroke volume blood velocity (SVV, Doppler ultrasound) were assessed during supine 30 degrees (5 min) and 60 degrees (5-10 min) HUT positions in 15 individuals who successfully completed the pre-HDBR test without evidence of orthostatic intolerance. Subjects were classified as being orthostatically tolerant (OT, n = 9) or intolerant (OI, n = 6) following the post-HDBR test. MSNA, BP, and SVV during supine and HUT postures were not altered in the OT group. Hypotension during 60 degrees HUT in the post-bed rest test for the OI group (P < 0.05) was associated with a blunted increase in MSNA (P < 0.05). SVV was reduced following HDBR in the OI group (main effect of HDBR, P < 0.02). The data support the hypothesis that bed rest-induced orthostatic intolerance is related to an inadequate increase in sympathetic discharge that cannot compensate for a greater postural reduction in stroke volume.
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Affiliation(s)
- J K Shoemaker
- Section of Cardiology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey 17033, Pennsylvania, USA.
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Pavy-Le Traon A, Louisy F, Vasseur-Clausen P, Güell A, Gharib C. Contributory factors to orthostatic intolerance after simulated weightlessness. CLINICAL PHYSIOLOGY (OXFORD, ENGLAND) 1999; 19:360-8. [PMID: 10516886 DOI: 10.1046/j.1365-2281.1999.00189.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Various factors may contribute to orthostatic intolerance (OI) observed after space flights or simulated weightlessness such as bed rest experiments: individual physical and physiological factors (arterial blood pressure (BP), height), physiological changes induced by real or simulated weightlessness (hypovolaemia, increase in venous distensibility), and space flight or simulation conditions (duration and counter-measure application). Our purpose was to test which of these factors were dominant in contributing to the OI. This was assessed in 47 healthy men participating in bed rest experiments of 4, 14, 28, 30 and 42 days, with or without counter-measures (medical stockings, lower-body negative pressure (LBNP), LBNP + muscular exercise). Nineteen subjects did not finish the orthostatic test (60 degrees head-up tilt or stand test) after bed rest. The occurrence of OI was associated with greater height, low resting BP, greater changes in resting lower-limb venous distensibility throughout the bed rest, and absence of counter-measures.
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Affiliation(s)
- A Pavy-Le Traon
- Laboratoire de Physiologie de l'Environnement, Faculté de Médecine Grange Blanche, Université Claude Bernard, Lyon, France
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Toussirot E, Bahjaoui-Bouhaddi M, Poncet JC, Cappelle S, Henriet MT, Wendling D, Regnard J. Abnormal autonomic cardiovascular control in ankylosing spondylitis. Ann Rheum Dis 1999; 58:481-7. [PMID: 10419866 PMCID: PMC1752931 DOI: 10.1136/ard.58.8.481] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE This study was aimed at assessing the contribution of the autonomic nervous system to adjustments of cardiovascular function in patients with ankylosing spondylitis (AS). METHODS In 18 AS patients (mean age: 34.9; mean disease duration: 6.4 years) and 13 healthy controls (mean age: 31.7) the changes of heart rate (HR) with deep breathing (E/I ratio) and standing up (30/15 ratio) were recorded. The slope of cardiac baroreflex, the times series of blood pressure and HR values upon lying and standing, and venous plasma concentrations of catecholamines were also analysed. Erythrocyte sedimentation rate (ESR), plasma C reactive protein (CRP) concentration and a clinical index (BASDAI score) were used to assess the degree of disease activity in patients. RESULTS In the standing patients, blood pressure was found to decrease progressively (p< 0.001). Furthermore, the patients with a BASDAI score > 5 had a higher heart rate than patients with a BASDAI score < 5 (p<0.02), and there was a trend for a similar difference when patients were classified according to their ESR and CRP. Plasma catecholamine concentrations and the E/I ratio were not different in patients from controls. The 30/15 ratio and the slope of the spontaneous baroreflex during standing were both lower in AS patients than controls (p< 0.01). CONCLUSIONS This study demonstrated a change in autonomic nervous system function of AS patients, with a decreased parasympathetic activity, as evidenced by higher HR and lower baroreflex slope. As these significant deviances were mainly observed in patients with more active (or more inflammatory) disease, the autonomic nervous system involvement could be related to the inflammatory process. This autonomic strain may be related to the cardiac involvement in AS patients.
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Affiliation(s)
- E Toussirot
- Department of Rheumatology, Centre Hospitalier Universitaire J Minjoz, Boulevard Fleming, 25030 Besançon Cédex, France
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Maillet A, Pavy-Le Traon A. MEDES clinical research facility as a tool to prepare ISSA space flights. ACTA ASTRONAUTICA 1998; 43:321-328. [PMID: 11541934 DOI: 10.1016/s0094-5765(98)00164-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This new multi-disciplinary medical experimentation center provides the ideal scientific, medical and technical environment required for research programs and to prepare international space station Alpha (ISSA) missions, where space and healthcare industries can share their expertise. Different models are available to simulate space flight effects (bed-rest, confinement,...). This is of particular interest for research in Human psychology, physiology, physiopathology and ergonomics, validation of biomedical materials and procedures, testing of drugs, and other healthcare related products. This clinical research facility (CRF) provides valuable services in various fields of Human research requiring healthy volunteers. CRF is widely accessible to national and international, scientific, medical and industrial organisations. Furthermore, users have at their disposal the multi-disciplinary skills of MEDES staff and all MEDES partners on a single site.
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Affiliation(s)
- A Maillet
- Clinique Spatiale-MEDES, Toulouse, France.
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