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Paladugu P, Ong J, Kumar R, Waisberg E, Zaman N, Kamran SA, Tavakkoli A, Rivolta MC, Nelson N, Yoo T, Douglas VP, Douglas K, Song A, Tso H, Lee AG. Lower body negative pressure as a research tool and countermeasure for the physiological effects of spaceflight: A comprehensive review. LIFE SCIENCES IN SPACE RESEARCH 2024; 42:8-16. [PMID: 39067995 DOI: 10.1016/j.lssr.2024.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 03/07/2024] [Accepted: 03/31/2024] [Indexed: 07/30/2024]
Abstract
Lower Body Negative Pressure (LBNP) redistributes blood from the upper body to the lower body. LBNP may prove to be a countermeasure for the multifaceted physiological changes endured by astronauts during spaceflight related to cephalad fluid shift. Over more than five decades, beginning with the era of Skylab, advancements in LBNP technology have expanded our understanding of neurological, ophthalmological, cardiovascular, and musculoskeletal adaptations in space, with particular emphasis on mitigating issues such as bone loss. To date however, no comprehensive review has been conducted that chronicles the evolution of this technology or elucidates the broad-spectrum potential of LBNP in managing the diverse physiological challenges encountered in the microgravity environment. Our study takes a chronological perspective, systematically reviewing the historical development and application of LBNP technology in relation to the various pathophysiological impacts of spaceflight. The primary objective is to illustrate how this technology, as it has evolved, offers an increasingly sophisticated lens through which to interpret the systemic effects of space travel on human physiology. We contend that the insights gained from LBNP studies can significantly aid in formulating targeted and effective countermeasures to ensure the health and safety of astronauts. Ultimately, this paper aspires to promote a more cohesive understanding of the broad applicability of LBNP as a countermeasure against multiple bodily effects of space travel, thereby contributing to a safer and more scientifically informed approach to human space exploration.
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Affiliation(s)
- Phani Paladugu
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; Sidney Kimmel Medical College, Philadelphia, PA, United States
| | - Joshua Ong
- Michigan Medicine, University of Michigan, Ann Arbor, MI, United States
| | - Rahul Kumar
- University of Miami, Coral Gables, FL, United States
| | - Ethan Waisberg
- University College Dublin School of Medicine, Belfield, Dublin, Ireland
| | - Nasif Zaman
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | - Sharif Amit Kamran
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | - Alireza Tavakkoli
- Human-Machine Perception Laboratory, Department of Computer Science and Engineering, University of Nevada, Reno, Reno, NV, United States
| | | | - Nicolas Nelson
- Sidney Kimmel Medical College, Philadelphia, PA, United States
| | - Taehwan Yoo
- Sidney Kimmel Medical College, Philadelphia, PA, United States
| | | | - Konstantinos Douglas
- First Department of Ophthalmology, Gennimatas General Hospital, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
| | - Amy Song
- University of Illinois College of Medicine, Chicago, IL, United States
| | - Hanna Tso
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Andrew G Lee
- Center for Space Medicine, Baylor College of Medicine, Houston, TX, United States; Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, United States; The Houston Methodist Research Institute, Houston Methodist Hospital, Houston, TX, United States; Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY, United States; Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX, United States; University of Texas MD Anderson Cancer Center, Houston, TX, United States; Texas A&M College of Medicine, TX, United States; Department of Ophthalmology, The University of Iowa Hospitals and Clinics, Iowa City, IA, United States.
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Morris PD, Anderton RA, Marshall-Goebel K, Britton JK, Lee SMC, Smith NP, van de Vosse FN, Ong KM, Newman TA, Taylor DJ, Chico T, Gunn JP, Narracott AJ, Hose DR, Halliday I. Computational modelling of cardiovascular pathophysiology to risk stratify commercial spaceflight. Nat Rev Cardiol 2024:10.1038/s41569-024-01047-5. [PMID: 39030270 DOI: 10.1038/s41569-024-01047-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/30/2024] [Indexed: 07/21/2024]
Abstract
For more than 60 years, humans have travelled into space. Until now, the majority of astronauts have been professional, government agency astronauts selected, in part, for their superlative physical fitness and the absence of disease. Commercial spaceflight is now becoming accessible to members of the public, many of whom would previously have been excluded owing to unsatisfactory fitness or the presence of cardiorespiratory diseases. While data exist on the effects of gravitational and acceleration (G) forces on human physiology, data on the effects of the aerospace environment in unselected members of the public, and particularly in those with clinically significant pathology, are limited. Although short in duration, these high acceleration forces can potentially either impair the experience or, more seriously, pose a risk to health in some individuals. Rather than expose individuals with existing pathology to G forces to collect data, computational modelling might be useful to predict the nature and severity of cardiovascular diseases that are of sufficient risk to restrict access, require modification, or suggest further investigation or training before flight. In this Review, we explore state-of-the-art, zero-dimensional, compartmentalized models of human cardiovascular pathophysiology that can be used to simulate the effects of acceleration forces, homeostatic regulation and ventilation-perfusion matching, using data generated by long-arm centrifuge facilities of the US National Aeronautics and Space Administration and the European Space Agency to risk stratify individuals and help to improve safety in commercial suborbital spaceflight.
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Affiliation(s)
- Paul D Morris
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK.
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
| | - Ryan A Anderton
- Medical Department, Spaceflight, UK Civil Aviation Authority, Gatwick, UK
| | - Karina Marshall-Goebel
- The National Aeronautics and Space Administration (NASA) Johnson Space Center, Houston, TX, USA
| | - Joseph K Britton
- Aerospace Medicine Specialist Wing, Royal Air Force (RAF) Centre of Aerospace Medicine, Henlow, UK
| | - Stuart M C Lee
- KBR, Human Health Countermeasures Element, NASA Johnson Space Center, Houston, TX, USA
| | - Nicolas P Smith
- Victoria University of Wellington, Wellington, New Zealand
- Auckland Bioengineering Institute, Auckland, New Zealand
| | - Frans N van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - Karen M Ong
- Virgin Galactic Medical, Truth or Consequences, NM, USA
| | - Tom A Newman
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Daniel J Taylor
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
| | - Tim Chico
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Julian P Gunn
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Andrew J Narracott
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - D Rod Hose
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
| | - Ian Halliday
- Division of Clinical Medicine, University of Sheffield, Sheffield, UK
- Insigneo Institute, University of Sheffield, Sheffield, UK
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3
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Takeda R, Hissen SL, Akins JD, Washio T, Hearon CM, MacNamara JP, Sarma S, Levine BD, Fadel PJ, Fu Q. Sympathetic Neural Control at Rest and During the Cold Pressor Test in Patients With Heart Failure With Preserved Ejection Fraction. Hypertension 2024; 81:917-926. [PMID: 38385250 PMCID: PMC10954398 DOI: 10.1161/hypertensionaha.123.21918] [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: 08/14/2023] [Accepted: 02/06/2024] [Indexed: 02/23/2024]
Abstract
BACKGROUND We tested the hypothesis that patients with heart failure with preserved ejection fraction (HFpEF) would have greater muscle sympathetic nerve activity (MSNA) at rest and sympathetic reactivity during a cold pressor test compared with non-heart failure controls. Further, given the importance of the baroreflex modulation of MSNA in the control of blood pressure (BP), we hypothesized that patients with HFpEF would exhibit a reduced sympathetic baroreflex sensitivity. METHODS Twenty-eight patients with HFpEF and 44 matched controls (mean±SD: 71±8 versus 70±7 years; 9 men/19 women versus 16 men/28 women) were studied. BP, heart rate, and MSNA (microneurography) were measured during 6 to 10 minutes of supine rest and the 2-minute cold pressor test. Spontaneous sympathetic baroreflex sensitivity was assessed during supine rest. RESULTS Patients with HFpEF had higher resting MSNA burst frequency (39±14 versus 31±12 bursts/min; P=0.020) and lower sympathetic baroreflex sensitivity (-2.83±0.76 versus -3.57±1.19 bursts/100 heartbeats/mm Hg; P=0.019) than controls, but burst incidence was not different between groups (56±19 versus 50±20 bursts/100 heartbeats; P=0.179). During the cold pressor test, increases in MSNA indices did not differ between groups (P=0.135-0.998), but patients had a smaller increase in diastolic BP (Δ4±6 versus Δ14±11 mm Hg; P<0.001) compared with controls. CONCLUSIONS Despite augmented resting MSNA burst frequency, burst incidence was not significantly different between groups, and sympathetic baroreflex sensitivity was reduced in patients with HFpEF. Furthermore, patients had preserved sympathetic reactivity but attenuated diastolic BP responses during the cold pressor test. These data suggest that, during physiological stress, sympathetic reactivity is intact, but the peripheral pathway for sympathetic vasoconstriction may be impaired in HFpEF.
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Affiliation(s)
- Ryosuke Takeda
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sarah L. Hissen
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - John D. Akins
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Takuro Washio
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Christopher M. Hearon
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - James P. MacNamara
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Satyam Sarma
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Paul J. Fadel
- University of Texas at Arlington, Arlington, Texas, USA
| | - Qi Fu
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Mastrandrea CJ, Greaves DK, Shoemaker JK, Blaber AP, Arbeille P, Hughson RL. Lower body negative pressure identifies altered central vein characteristics without accompanying changes to baroreflexes in astronauts within hours of landing. Sci Rep 2024; 14:1215. [PMID: 38216637 PMCID: PMC10786840 DOI: 10.1038/s41598-024-51643-1] [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: 08/08/2023] [Accepted: 01/08/2024] [Indexed: 01/14/2024] Open
Abstract
Cardiovascular deconditioning and altered baroreflexes predispose returning astronauts to Orthostatic Intolerance. We assessed 7 astronauts (1 female) before and following long-duration spaceflight (146 ± 43 days) with minimal upright posture prior to testing. We applied lower body negative pressure (LBNP) of up to - 30 mmHg to supine astronauts instrumented for continual synchronous measurements of cardiovascular variables, and intermittent imaging the Portal Vein (PV) and Inferior Vena Cava (IVC). During supine rest without LBNP, postflight elevations to total peripheral resistance (TPR; 15.8 ± 4.6 vs. 20.8 ± 7.1 mmHg min/l, p < 0.05) and reductions in stroke volume (SV; 104.4 ± 16.7 vs. 87.4 ± 11.5 ml, p < 0.05) were unaccompanied by changes to heart rate (HR) or estimated central venous pressure (CVP). Small increases to systolic blood pressure (SBP) and diastolic blood pressure (DBP) were not statistically significant. Autoregressive moving average modelling (ARMA) during LBNP did not identify differences to either arterial (DBP → TPR and SBP → HR) or cardiopulmonary (CVP → TPR) baroreflexes consistent with intact cardiovascular control. On the other hand, IVC and PV diameter-CVP relationships during LBNP revealed smaller diameter for a given CVP postflight consistent with altered postflight venous wall dynamics.
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Affiliation(s)
- C J Mastrandrea
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada.
- University of Waterloo, Waterloo, ON, Canada.
| | - D K Greaves
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada
| | - J K Shoemaker
- School of Kinesiology and Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - A P Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - P Arbeille
- Unite Médecine Physiologie Spatiale, CERCOM, Faculté de Médecine-Université de Tours, Tours, France
| | - R L Hughson
- Schlegel-UW Research Institute for Aging, Waterloo, ON, Canada
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Krittanawong C, Isath A, Kaplin S, Virk HUH, Fogg S, Wang Z, Shepanek M, Scheuring RA, Lavie CJ. Cardiovascular disease in space: A systematic review. Prog Cardiovasc Dis 2023; 81:33-41. [PMID: 37531984 DOI: 10.1016/j.pcad.2023.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 07/29/2023] [Indexed: 08/04/2023]
Abstract
BACKGROUND With expanding commercial space programs, uncertainty remains about the cardiovascular effects of space environmental exposures including microgravity, confinement, isolation, space radiation, and altered bacterial virulence. Current limited data suggests additional health threats compared to Earth. METHODS We systematically reviewed PubMed, CENTRAL, Web of Science, EMBASE and Cochrane databases for prospective studies on spaceflight and cardiovascular outcomes. Search terms combined cardiovascular disease topics with spaceflight concepts. No date or language restrictions were imposed. RESULTS 35 studies representing 2696 space travelers met inclusion criteria. Studies were grouped into spaceflight associations with: atherosclerosis, mortality, cardiac function, orthostatic intolerance, and arrhythmias. Atherosclerosis evidence was limited, with animal studies linking space radiation to endothelial damage, oxidative stress, and inflammation. However, human data showed no significantly increased atherosclerotic disease in astronauts. Mortality studies demonstrated lower cardiovascular mortality in astronauts compared to the general population however there was conflicting data. Cardiac function studies revealed physiologic ventricular atrophy, increased arterial stiffness, and altered blood flow distribution attributed to microgravity exposure. Effects appeared transient and reversible post-flight. Orthostatic intolerance studies found astronauts experienced altered heart rate variability, baroreflex response, and blood pressure changes post-flight. Arrhythmia studies showed increased ventricular ectopy during spaceflight, but limited data on long term flights. CONCLUSIONS Environmental space hazards impact the cardiovascular system through multiple mechanisms. Microgravity causes cardiac atrophy and orthostatic intolerance while space radiation may potentially accelerate atherosclerosis. Further research is needed, especially regarding long-term spaceflights.
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Affiliation(s)
| | - Ameesh Isath
- Department of Cardiology, Westchester Medical Centre and New York Medical College, Valhalla, NY, USA
| | - Scott Kaplin
- Cardiology Division, NYU Langone Health and NYU School of Medicine, New York, NY, USA
| | - Hafeez Ul Hassan Virk
- Harrington Heart & Vascular Institute, Case Western Reserve University, University Hospitals Cleveland Medical Center, OH, USA
| | - Sonya Fogg
- Library and Learning Resource Center, Texas Heart Institute, Houston, USA
| | - Zhen Wang
- Mayo Clinic Evidence-based Practice Center, Rochester, MN, USA; Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery; Division of Health Care Policy and Research, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Marc Shepanek
- Office of the Chief Health and Medical Officer, NASA, Washington, DC 20546, USA
| | | | - Carl J Lavie
- John Ochsner Heart and Vascular Institute, Ochsner Clinical School, The University of Queensland School of Medicine, New Orleans, LA, USA
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6
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Hoenemann JN, Moestl S, Diedrich A, Mulder E, Frett T, Petrat G, Pustowalow W, Arz M, Schmitz MT, Heusser K, Lee SMC, Jordan J, Tank J, Hoffmann F. Impact of daily artificial gravity on autonomic cardiovascular control following 60-day head-down tilt bed rest. Front Cardiovasc Med 2023; 10:1250727. [PMID: 37953766 PMCID: PMC10634666 DOI: 10.3389/fcvm.2023.1250727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/04/2023] [Indexed: 11/14/2023] Open
Abstract
Impaired cardiovascular autonomic control following space flight or immobilization may limit the ability to cope with additional hemodynamic stimuli. Head-down tilt bedrest is an established terrestrial analog for space flight and offers the opportunity to test potential countermeasures for autonomic cardiovascular deconditioning. Previous studies revealed a possible benefit of daily artificial gravity on cardiovascular autonomic control following head-down tilt bedrest, but there is a need for efficiency in a long-term study before an artificial gravity facility would be brought to space. We hypothesized that artificial gravity through short-arm centrifugation attenuates functional adaptions of autonomic function during head-down tilt bed rest. 24 healthy persons (8 women, 33.4 ± 9.3 years, 24.3 ± 2.1 kg/m2) participated in the 60-day head-down tilt bed rest (AGBRESA) study. They were assigned to three groups, 30 min/day continuous, or 6(5 min intermittent short-arm centrifugation, or a control group. We assessed autonomic cardiovascular control in the supine position and in 5 minutes 80° head-up tilt position before and immediately after bed rest. We computed heart rate variability (HRV) in the time (rmssd) and frequency domain, blood pressure variability, and baroreflex sensitivity (BRS). RR interval corrected rmssd was reduced supine (p = 0.0358) and during HUT (p = 0.0161). Heart rate variability in the high-frequency band (hf-RRI; p = 0.0004) and BRS (p < 0.0001) decreased, whereas blood pressure variability in the low-frequency band (lf-SBP, p = 0.0008) increased following bedrest in all groups. We did not detect significant interactions between bedrest and interventions. We conclude that up to daily 30 min of artificial gravity on a short-arm centrifuge with 1Gz at the center of mass do not suffice to prevent changes in autonomic cardiovascular control following 60-day of 6° head-down tilt bed rest. Clinical Trial Registration: https://drks.de/search/en/trial/DRKS00015677, identifier, DRKS00015677.
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Affiliation(s)
- J.-N. Hoenemann
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Department of Internal Medicine III, Division of Cardiology, Pneumology, Angiology, and Intensive Care, University of Cologne, Cologne, Germany
| | - S. Moestl
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - A. Diedrich
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Service, Vanderbilt University, Nashville, TN, United States
| | - E. Mulder
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - T. Frett
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - G. Petrat
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - W. Pustowalow
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - M. Arz
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - M.-T. Schmitz
- Institute of Medical Biometry, Informatics and Epidemiology (IMBIE), University Hospital Bonn, Bonn, Germany
| | - K. Heusser
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - S. M. C. Lee
- Wyle Laboratories, Life Sciences and Systems Division, Houston, TX, United States
| | - J. Jordan
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Head of Aerospace Medicine, University of Cologne, Germany, Cologne
| | - J. Tank
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - F. Hoffmann
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
- Department of Internal Medicine III, Division of Cardiology, Pneumology, Angiology, and Intensive Care, University of Cologne, Cologne, Germany
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7
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Olde Engberink RHG, van Oosten PJ, Weber T, Tabury K, Baatout S, Siew K, Walsh SB, Valenti G, Chouker A, Boutouyrie P, Heer M, Jordan J, Goswami N. The kidney, volume homeostasis and osmoregulation in space: current perspective and knowledge gaps. NPJ Microgravity 2023; 9:29. [PMID: 37005397 PMCID: PMC10067832 DOI: 10.1038/s41526-023-00268-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 03/13/2023] [Indexed: 04/04/2023] Open
Abstract
Although we have sent humans into space for more than 50 years crucial questions regarding kidney physiology, volume regulation and osmoregulation remain unanswered. The complex interactions between the renin-angiotensin-aldosterone system, the sympathetic nervous system, osmoregulatory responses, glomerular function, tubular function, and environmental factors such as sodium and water intake, motion sickness and ambient temperature make it difficult to establish the exact effect of microgravity and the subsequent fluid shifts and muscle mass loss on these parameters. Unfortunately, not all responses to actual microgravity can be reproduced with head-down tilt bed rest studies, which complicates research on Earth. Better understanding of the effects of microgravity on kidney function, volume regulation and osmoregulation are needed with the advent of long-term deep space missions and planetary surface explorations during which orthostatic intolerance complaints or kidney stone formation can be life-threatening for astronauts. Galactic cosmic radiation may be a new threat to kidney function. In this review, we summarise and highlight the current understandings of the effects of microgravity on kidney function, volume regulation and osmoregulation and discuss knowledge gaps that future studies should address.
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Affiliation(s)
- Rik H G Olde Engberink
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands.
- Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands.
| | - Paula J van Oosten
- Amsterdam UMC location University of Amsterdam, Department of Internal Medicine, Section of Nephrology, Meibergdreef 9, Amsterdam, The Netherlands
- Amsterdam Cardiovascular Sciences, Microcirculation, Amsterdam, The Netherlands
| | - Tobias Weber
- Space Medicine Team, European Astronaut Centre (EAC), Cologne, Germany
- KBR GmbH, Cologne, Germany
| | - Kevin Tabury
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK CEN, Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK CEN, Mol, Belgium
| | - Keith Siew
- London Tubular Centre, UCL Department of Renal Medicine, University College London, London, UK
| | - Stephen B Walsh
- London Tubular Centre, UCL Department of Renal Medicine, University College London, London, UK
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Alexander Chouker
- Laboratory of Translational Research Stress and Immunity, Department of Anesthesiology, Hospital of the Ludwig-Maximilians-University (LUM), Munich, Germany
| | - Pierre Boutouyrie
- Université Paris Cité, Inserm, PARCC, F-75015, Paris, France
- Service de Pharmacologie, DMU CARTE, AP-HP, Hôpital Européen Georges Pompidou, FR-75015, Paris, France
| | - Martina Heer
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
- Institute of Nutritional and Food Sciences, University of Bonn, Bonn, Germany
| | - Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center (DLR) and University of Cologne, Cologne, Germany
| | - Nandu Goswami
- Gravitational Physiology and Medicine Research Unit, Division of Physiology, Otto Löwi Research Center of Vascular Biology, Inflammation, and Immunity, Medical University of Graz, Graz, Austria
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
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8
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Hettrick H, Aviles F. Microgravity and Lymphatics: Why Space Programs Need Lymphedema Physiology Specialists. Lymphat Res Biol 2023. [PMID: 36622762 DOI: 10.1089/lrb.2022.0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Background: The resurgence of space travel in the recent years, both through formally trained astronauts on the International Space Station and the civilian space race to send astrocivilians to Low Earth Orbit and beyond, beckons the need to understand the role of the lymphatic system and role of endothelial glycocalyx when subjected to gravitational alterations. Methods and Results: A comprehensive narrative review of the literature explores a call to action for research and countermeasure development to support the health and well-being of humans subjected to space flight, with particular attention to the role of the lymphatic system and endothelial glycocalyx. Emerging evidence suggests a link between the dysfunction experienced with various physiological processes in microgravity, highlighting the need for more research exploring the role of the lymphatic system in the extremes of gravity and countermeasure development to reduce dysregulation. Conclusion: The synergistic and interdependent relationship of these structures are fundamental to health in space and on Earth.
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Affiliation(s)
- Heather Hettrick
- Department of Physical Therapy, Nova Southeastern University, Fort Lauderdale, Florida, USA
| | - Frank Aviles
- Wound Care Service Line Director, Natchitoches Regional Medical Center, Natchitoches, Louisiana, USA
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9
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Sy MR, Keefe JA, Sutton JP, Wehrens XHT. Cardiac function, structural, and electrical remodeling by microgravity exposure. Am J Physiol Heart Circ Physiol 2023; 324:H1-H13. [PMID: 36399385 PMCID: PMC9762974 DOI: 10.1152/ajpheart.00611.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/19/2022]
Abstract
Space medicine is key to the human exploration of outer space and pushes the boundaries of science, technology, and medicine. Because of harsh environmental conditions related to microgravity and other factors and hazards in outer space, astronauts and spaceflight participants face unique health and medical challenges, including those related to the heart. In this review, we summarize the literature regarding the effects of spaceflight on cardiac structure and function. We also provide an in-depth review of the literature regarding the effects of microgravity on cardiac calcium handling. Our review can inform future mechanistic and therapeutic studies and is applicable to other physiological states similar to microgravity such as prolonged horizontal bed rest and immobilization.
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Affiliation(s)
- Mary R Sy
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas
| | - Joshua A Keefe
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas
| | - Jeffrey P Sutton
- Center for Space Medicine, Baylor College of Medicine, Houston, Texas
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas
- Department of Integrative Physiology, Baylor College of Medicine, Houston, Texas
- Center for Space Medicine, Baylor College of Medicine, Houston, Texas
- Department of Medicine, Baylor College of Medicine, Houston, Texas
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas
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10
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Inbaraj G, Udupa K, Vasuki PP, Nalini A, Sathyaprabha TN. Resting heart rate variability as a diagnostic marker of cardiovascular dysautonomia in postural tachycardia syndrome. J Basic Clin Physiol Pharmacol 2023; 34:103-109. [PMID: 36367272 DOI: 10.1515/jbcpp-2022-0069] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022]
Abstract
OBJECTIVES Postural orthostatic tachycardia syndrome (POTS) is a disorder of the autonomic nervous system characterised by orthostatic intolerance and orthostatic tachycardia without hypotension. Heart rate variability (HRV) is the most reliable and objective tool for assessing autonomic dysfunction severity. In the present study, we aimed to investigate HRV changes in resting supine position, predicting severity and cardiovascular risk in patients with POTS. METHODS We compared 100 POTS patients with 160 healthy controls matched for age and gender in a case-control design. Along with clinical characterization, heart rate variability was evaluated using ambulatory 5 min ECG in lead II and expressed in frequency and time-domain measures. RESULTS The resting heart rate of patients with POTS was significantly higher than that of healthy controls. In HRV measures, root mean square successive difference of RR intervals (RMSSD), total and high frequency (HF) powers were statistically lower with an increased low frequency (LF) to high-frequency ratio in patients with POTS compared to healthy controls. Further, stepwise logistic regression analysis showed increased basal HR and LF/HF as significant predictors of POTS and its severity. CONCLUSIONS This is the first study on a large cohort of patients with POTS from India wherein HRV was assessed. The study showed reduced parasympathetic activity and increased sympathetic activity in patients with POTS compared to healthy controls. These findings of increased resting heart rate and LF/HF were found to be potential predictors of POTS and future cardiovascular risks, which need to be replicated in a larger and more homogenized cohort.
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Affiliation(s)
- Ganagarajan Inbaraj
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Kaviraja Udupa
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | | | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Talakad N Sathyaprabha
- Department of Neurophysiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
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11
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Krittanawong C, Singh NK, Scheuring RA, Urquieta E, Bershad EM, Macaulay TR, Kaplin S, Dunn C, Kry SF, Russomano T, Shepanek M, Stowe RP, Kirkpatrick AW, Broderick TJ, Sibonga JD, Lee AG, Crucian BE. Human Health during Space Travel: State-of-the-Art Review. Cells 2022; 12:cells12010040. [PMID: 36611835 PMCID: PMC9818606 DOI: 10.3390/cells12010040] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
The field of human space travel is in the midst of a dramatic revolution. Upcoming missions are looking to push the boundaries of space travel, with plans to travel for longer distances and durations than ever before. Both the National Aeronautics and Space Administration (NASA) and several commercial space companies (e.g., Blue Origin, SpaceX, Virgin Galactic) have already started the process of preparing for long-distance, long-duration space exploration and currently plan to explore inner solar planets (e.g., Mars) by the 2030s. With the emergence of space tourism, space travel has materialized as a potential new, exciting frontier of business, hospitality, medicine, and technology in the coming years. However, current evidence regarding human health in space is very limited, particularly pertaining to short-term and long-term space travel. This review synthesizes developments across the continuum of space health including prior studies and unpublished data from NASA related to each individual organ system, and medical screening prior to space travel. We categorized the extraterrestrial environment into exogenous (e.g., space radiation and microgravity) and endogenous processes (e.g., alteration of humans' natural circadian rhythm and mental health due to confinement, isolation, immobilization, and lack of social interaction) and their various effects on human health. The aim of this review is to explore the potential health challenges associated with space travel and how they may be overcome in order to enable new paradigms for space health, as well as the use of emerging Artificial Intelligence based (AI) technology to propel future space health research.
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Affiliation(s)
- Chayakrit Krittanawong
- Department of Medicine and Center for Space Medicine, Section of Cardiology, Baylor College of Medicine, Houston, TX 77030, USA
- Translational Research Institute for Space Health, Houston, TX 77030, USA
- Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA
- Correspondence: or (C.K.); (B.E.C.); Tel.: +1-713-798-4951 (C.K.); +1-281-483-0123 (B.E.C.)
| | - Nitin Kumar Singh
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | | | - Emmanuel Urquieta
- Translational Research Institute for Space Health, Houston, TX 77030, USA
- Department of Emergency Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Eric M. Bershad
- Department of Neurology, Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Scott Kaplin
- Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA
| | - Carly Dunn
- Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stephen F. Kry
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | | | - Marc Shepanek
- Office of the Chief Health and Medical Officer, NASA, Washington, DC 20546, USA
| | | | - Andrew W. Kirkpatrick
- Department of Surgery and Critical Care Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | | | - Jean D. Sibonga
- Division of Biomedical Research and Environmental Sciences, NASA Lyndon B. Johnson Space Center, Houston, TX 77058, USA
| | - Andrew G. Lee
- Department of Ophthalmology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Department of Ophthalmology, Texas A and M College of Medicine, College Station, TX 77807, USA
- Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY 10021, USA
| | - Brian E. Crucian
- National Aeronautics and Space Administration (NASA) Johnson Space Center, Human Health and Performance Directorate, Houston, TX 77058, USA
- Correspondence: or (C.K.); (B.E.C.); Tel.: +1-713-798-4951 (C.K.); +1-281-483-0123 (B.E.C.)
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12
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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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13
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Pantalone D, Chiara O, Henry S, Cimbanassi S, Gupta S, Scalea T. Facing Trauma and Surgical Emergency in Space: Hemorrhagic Shock. Front Bioeng Biotechnol 2022; 10:780553. [PMID: 35845414 PMCID: PMC9283715 DOI: 10.3389/fbioe.2022.780553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 04/22/2022] [Indexed: 11/16/2022] Open
Abstract
Although the risk of trauma in space is low, unpredictable events can occur that may require surgical treatment. Hemorrhage can be a life-threatening condition while traveling to another planet and after landing on it. These exploration missions call for a different approach than rapid return to Earth, which is the policy currently adopted on the International Space Station (ISS) in low Earth orbit (LEO). Consequences are difficult to predict, given the still scarce knowledge of human physiology in such environments. Blood loss in space can deplete the affected astronaut’s physiological reserves and all stored crew supplies. In this review, we will describe different aspects of hemorrhage in space, and by comparison with terrestrial conditions, the possible solutions to be adopted, and the current state of the art.
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Affiliation(s)
- D. Pantalone
- Department of Experimental and Clinical Medicine, Fellow of the American College of Surgeons, Core Board and Head for Studies on Traumatic Events and Surgery in the European Space Agency-Topical Team on “Tissue Healing in Space Techniques for Promoting and Monitoring Tissue Repair and Regeneration” for Life Science Activities Agency, Assistant Professor in General Surgery, Specialist in Vascular Surgery, Emergency Surgery Unit–Trauma Team, Emergency Department–Careggi University Hospital, University of Florence, Florence, Italy
- *Correspondence: D. Pantalone,
| | - O. Chiara
- Fellow of the American College of Surgeons, Director of General Surgery–Trauma Team, ASST GOM Grande Ospedale Metropolitano Niguarda, Professor of Surgery, University of Milan, Milan, Italy
| | - S. Henry
- Fellow of the American College of Surgeons, Director Division of Wound Healing and Metabolism, R Adams Cowley Shock Trauma Center University of Maryland, Baltimore, MD, United States
| | - S. Cimbanassi
- Fellow of the American College of Surgeons, EMDM, Vice Director of General Surgery-Trauma Team, ASST GOM Grande Ospedale Metropolitano Niguarda, Milan, Italy
| | - S. Gupta
- Fellow of the American College of Surgeons, R Adams Cowl y Shock Trauma Center, University of Maryland, Baltimore, MD, United States
| | - T. Scalea
- Fellow of the American College of Surgeons, The Honorable Francis X. Kelly Distinguished Professor of Trauma Surgery.Physician-in-Chief, R Adams Cowley Shock Trauma Center, System Chief for Critical Care Services, University of Maryland Medical System, University of Maryland, Baltimore, MD, United States
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14
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Levine BD, Nicol ED, Davos CH. Space: The Final Frontier? Eur J Prev Cardiol 2022; 29:1396-1398. [PMID: 35711101 DOI: 10.1093/eurjpc/zwac125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Dallas and The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Edward D Nicol
- Department of Cardiology, Royal Brompton and Harefield NHS Foundation Trust, London, UK.,National Heart and Lung Institute, Imperial College, London, UK
| | - Constantinos H Davos
- Cardiovascular Research Laboratory, Biomedical Research Foundation, Academy of Athens, Athens, Greece
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15
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Jordan J, Limper U, Tank J. Cardiovascular autonomic nervous system responses and orthostatic intolerance in astronauts and their relevance in daily medicine. Neurol Sci 2022; 43:3039-3051. [PMID: 35194757 PMCID: PMC9018660 DOI: 10.1007/s10072-022-05963-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/17/2022] [Indexed: 11/12/2022]
Abstract
Background The harsh environmental conditions during space travel, particularly weightlessness, impose a major burden on the human body including the cardiovascular system. Given its importance in adjusting the cardiovascular system to environmental challenges, the autonomic nervous system has been in the focus of scientists and clinicians involved in human space flight. This review provides an overview on human autonomic research under real and simulated space conditions with a focus on orthostatic intolerance. Methods The authors conducted a targeted literature search using Pubmed. Results Overall, 120 articles were identified and included in the review. Conclusions Postflight orthostatic intolerance is commonly observed in astronauts and could pose major risks when landing on another celestial body. The phenomenon likely results from changes in volume status and adaptation of the autonomic nervous system to weightlessness. Over the years, various non-pharmacological and pharmacological countermeasures have been investigated. In addition to enabling safe human space flight, this research may have implications for patients with disorders affecting cardiovascular autonomic control on Earth.
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Affiliation(s)
- Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany. .,Aerospace Medicine, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Ulrich Limper
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany.,Department of Anesthesiology and Intensive Care Medicine, Merheim Medical Center, Hospitals of Cologne, University of Witten/Herdecke, Cologne, Germany
| | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany
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16
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Jirak P, Mirna M, Rezar R, Motloch LJ, Lichtenauer M, Jordan J, Binneboessel S, Tank J, Limper U, Jung C. How spaceflight challenges human cardiovascular health. Eur J Prev Cardiol 2022; 29:1399-1411. [PMID: 35148376 DOI: 10.1093/eurjpc/zwac029] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 01/08/2022] [Accepted: 02/06/2022] [Indexed: 11/14/2022]
Abstract
The harsh environmental conditions in space, particularly weightlessness and radiation exposure, can negatively affect cardiovascular function and structure. In the future, preventive cardiology will be crucial in enabling safe space travel. Indeed, future space missions destined to the Moon and from there to Mars will create new challenges to cardiovascular health while limiting medical management. Moreover, commercial spaceflight evolves rapidly such that older persons with cardiovascular risk factors will be exposed to space conditions. This review provides an overview on studies conducted in space and in terrestrial models, particularly head-down bedrest studies. These studies showed that weightlessness elicits a fluid shift towards the head, which likely predisposes to the spaceflight-associated neuro-ocular syndrome, neck vein thrombosis, and orthostatic intolerance after return to Earth. Moreover, cardiovascular unloading produces cardiopulmonary deconditioning which may be associated with cardiac atrophy. In addition to limiting physical performance, the mechanism further worsens orthostatic tolerance after return to Earth. Finally, space conditions may directly affect vascular health, however, the clinical relevance of these findings in terms of morbidity and mortality is unknown. Targeted preventive measures, which are referred to as countermeasures in aerospace medicine, and technologies to identify vascular risks early on will be required to maintain cardiovascular performance and health during future space missions.
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Affiliation(s)
- Peter Jirak
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Moritz Mirna
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Richard Rezar
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Lukas J Motloch
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Michael Lichtenauer
- Clinic II for Internal Medicine, University Hospital Salzburg, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Medical Faculty, University of Cologne, Germany
| | - Stephan Binneboessel
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Duesseldorf, Germany
| | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany
| | - Ulrich Limper
- Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany.,Department of Anaesthesiology and Critical Care Medicine, Merheim Medical Center, Witten/Herdecke University, Cologne, Germany
| | - Christian Jung
- Division of Cardiology, Pulmonology, and Vascular Medicine, Medical Faculty, University Duesseldorf, Germany
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17
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Baran R, Marchal S, Garcia Campos S, Rehnberg E, Tabury K, Baselet B, Wehland M, Grimm D, Baatout S. The Cardiovascular System in Space: Focus on In Vivo and In Vitro Studies. Biomedicines 2021; 10:59. [PMID: 35052739 PMCID: PMC8773383 DOI: 10.3390/biomedicines10010059] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/24/2021] [Accepted: 12/25/2021] [Indexed: 12/13/2022] Open
Abstract
On Earth, humans are subjected to a gravitational force that has been an important determinant in human evolution and function. During spaceflight, astronauts are subjected to several hazards including a prolonged state of microgravity that induces a myriad of physiological adaptations leading to orthostatic intolerance. This review summarises all known cardiovascular diseases related to human spaceflight and focusses on the cardiovascular changes related to human spaceflight (in vivo) as well as cellular and molecular changes (in vitro). Upon entering microgravity, cephalad fluid shift occurs and increases the stroke volume (35-46%) and cardiac output (18-41%). Despite this increase, astronauts enter a state of hypovolemia (10-15% decrease in blood volume). The absence of orthostatic pressure and a decrease in arterial pressures reduces the workload of the heart and is believed to be the underlying mechanism for the development of cardiac atrophy in space. Cellular and molecular changes include altered cell shape and endothelial dysfunction through suppressed cellular proliferation as well as increased cell apoptosis and oxidative stress. Human spaceflight is associated with several cardiovascular risk factors. Through the use of microgravity platforms, multiple physiological changes can be studied and stimulate the development of appropriate tools and countermeasures for future human spaceflight missions in low Earth orbit and beyond.
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Affiliation(s)
- Ronni Baran
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus, Denmark; (R.B.); (D.G.)
| | - Shannon Marchal
- Department of Astronomy, Catholic University of Leuven, 3000 Leuven, Belgium;
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium; (E.R.); (K.T.); (B.B.)
| | - Sebastian Garcia Campos
- Department of Microgravity and Translational Regenerative Medicine, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany; (S.G.C.); (M.W.)
- Research Group ‘Magdeburger Arbeitsgemeinschaft für Forschung unter Raumfahrt- und Schwerelosigkeitsbedingungen’ (MARS), Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Emil Rehnberg
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium; (E.R.); (K.T.); (B.B.)
- Department of Molecular Biotechnology, Ghent University, 9000 Ghent, Belgium
| | - Kevin Tabury
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium; (E.R.); (K.T.); (B.B.)
- Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, USA
| | - Bjorn Baselet
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium; (E.R.); (K.T.); (B.B.)
| | - Markus Wehland
- Department of Microgravity and Translational Regenerative Medicine, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany; (S.G.C.); (M.W.)
- Research Group ‘Magdeburger Arbeitsgemeinschaft für Forschung unter Raumfahrt- und Schwerelosigkeitsbedingungen’ (MARS), Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Daniela Grimm
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000 Aarhus, Denmark; (R.B.); (D.G.)
- Department of Microgravity and Translational Regenerative Medicine, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany; (S.G.C.); (M.W.)
- Research Group ‘Magdeburger Arbeitsgemeinschaft für Forschung unter Raumfahrt- und Schwerelosigkeitsbedingungen’ (MARS), Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany
| | - Sarah Baatout
- Department of Astronomy, Catholic University of Leuven, 3000 Leuven, Belgium;
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium; (E.R.); (K.T.); (B.B.)
- Department of Molecular Biotechnology, Ghent University, 9000 Ghent, Belgium
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18
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Grassi G, Mancia G, Esler M. CENTRAL AND PERIPHERAL SYMPATHETIC ACTIVATION IN HEART FAILURE. Cardiovasc Res 2021; 118:1857-1871. [PMID: 34240147 DOI: 10.1093/cvr/cvab222] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/02/2021] [Indexed: 11/12/2022] Open
Abstract
The sympathetic nervous system overdrive occurring in heart failure has been reported since more than half a century. Refinements in the methodological approaches to assess human sympathetic neural function have allowed during recent years to better define various aspects related to the neuroadrenergic alteration. These include 1) the different participation of the individual regional sympathetic cardiovascular districts at the process, 2) the role of the central nervous system in determining the neuroadrenergic overdrive, 3) the involvement of baroreflex, cardiopulmonary reflex and chemoreflex mechanisms in the phoenomenon, which is also closely linked to inflammation and the immune reaction, 4) the relationships with the severity of the disease, its ischaemic or idiopathic nature and the preserved or reduced left ventricular ejection fraction and 5) the adverse functional and structural impact of the sympathetic activation on cardiovascular organs, such as the brain, the heart and the kidneys. Information have been also gained on the active role exerted by the sympathetic activation on the disease outcome and its potential relevance as target of the therapeutic interventions based on non-pharmacological, pharmacological and invasive approaches, including the renal denervation, the splanchnic sympathetic nerve ablation and the carotid baroreflex stimulation. The still undefined aspects of the neurogenic alterations and the unmet goals of the therapeutic approach having the sympathetic activation as a target of the intervention will be finally mentioned.
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Affiliation(s)
- Guido Grassi
- Clinica Medica, Department of Medicine and Surgery, University of Milano-Bicocca
| | - Giuseppe Mancia
- Policlinico di Monza and University Milano-Bicocca, Milan, Italy
| | - Murray Esler
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
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19
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Abstract
Unlike noradrenaline, the sympathetic neurotransmitter which overflows to the circulation, adrenaline (ADR) is a secreted hormone, with a low plasma concentration, and plasma concentration for biological action a log order lower than that of noradrenaline. The venous drainage of the left adrenal medulla into the left renal vein does expose this vein to uniquely high plasma ADR concentrations and possible risk of thrombosis at high rates of ADR secretion. There is typically a different timeframe for adrenal medullary and sympathetic nervous system responses: ADR release is short term in contrast with sympathetic activation persisting for years in heart failure and hypertension. The historic view of Walter Cannon, subject to recent review, that the sympathoadrenal system is a unified biological system, was deconstructed further with demonstration of frequent mismatching of adrenal medullary and sympathetic nervous responses. Under gravity stimulation with standing, there is prompt sympathetic activation without ADR release. In many diseases, notably obesity, hypertension, heart failure and depressive illness, an activated sympathetic nervous system and silent adrenal medulla coexist. The therapeutic corollary of this is that ADR blockade is much less commonly needed clinically than pharmacological antagonism of the sympathetic nervous system.
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20
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Barbic F, Minonzio M, Cairo B, Shiffer D, Zamuner AR, Cavalieri S, Dipaola F, Magnavita N, Porta A, Furlan R. Work Ability Assessment and Its Relationship with Cardiovascular Autonomic Profile in Postural Orthostatic Tachycardia Syndrome. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17217836. [PMID: 33114659 PMCID: PMC7662324 DOI: 10.3390/ijerph17217836] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 12/28/2022]
Abstract
Postural orthostatic tachycardia syndrome (POTS) negatively impacts quality of life. The excessive increase in cardiac sympathetic modulation during standing, which characterizes POTS patients, leads to many symptoms and signs of orthostatic intolerance. Little is known about the consequences of the disease on work performance and its relationship with individual autonomic profiles. Twenty-two POTS patients regularly engaged in working activity (20 females, age 36 ± 12 years) and 18 gender- and age-matched controls underwent a clinical evaluation and filled out the Work Ability Index (WAI) questionnaire. POTS patients completed the Composite Autonomic Symptom Score (COMPASS31) questionnaire, underwent continuous electrocardiogram, blood pressure and respiratory activity recordings while supine and during a 75° head-up tilt (HUT). A power spectrum analysis provided the index of cardiac sympatho-vagal balance (LF/HF). WAI scores were significantly reduced in POTS patients (29.84 ± 1.40) compared to controls (45.63 ± 0.53, p < 0.01). A significant inverse correlation was found between individual WAI and COMPASS31 scores (r = −0.46; p = 0.03), HUT increase in heart rate (r = −0.57; p = 0.01) and LF/HF (r = −0.55; p = 0.01). In POTS patients, the WAI scores were inversely correlated to the intensity of autonomic symptoms and to the excessive cardiac sympathetic activation induced by the gravitational stimulus.
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Affiliation(s)
- Franca Barbic
- Internal Medicine, Humanitas Clinical and Research Center—IRCCS, Via Manzoni 56, 20089 Rozzano-Milan, Italy; (M.M.); (D.S.); (F.D.); (R.F.)
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele-Milan, Italy
- Correspondence:
| | - Maura Minonzio
- Internal Medicine, Humanitas Clinical and Research Center—IRCCS, Via Manzoni 56, 20089 Rozzano-Milan, Italy; (M.M.); (D.S.); (F.D.); (R.F.)
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, 20122 Milan, Italy; (B.C.); (A.P.)
| | - Dana Shiffer
- Internal Medicine, Humanitas Clinical and Research Center—IRCCS, Via Manzoni 56, 20089 Rozzano-Milan, Italy; (M.M.); (D.S.); (F.D.); (R.F.)
| | | | - Silvia Cavalieri
- Department of Life Sciences & Public Health, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (S.C.); (N.M.)
| | - Franca Dipaola
- Internal Medicine, Humanitas Clinical and Research Center—IRCCS, Via Manzoni 56, 20089 Rozzano-Milan, Italy; (M.M.); (D.S.); (F.D.); (R.F.)
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele-Milan, Italy
| | - Nicola Magnavita
- Department of Life Sciences & Public Health, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (S.C.); (N.M.)
- Department of Woman, Children & Public Health, Fondazione Policlinico A. Gemelli—IRCCS, 00168 Rome, Italy
| | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, 20122 Milan, Italy; (B.C.); (A.P.)
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy
| | - Raffaello Furlan
- Internal Medicine, Humanitas Clinical and Research Center—IRCCS, Via Manzoni 56, 20089 Rozzano-Milan, Italy; (M.M.); (D.S.); (F.D.); (R.F.)
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele-Milan, Italy
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Patel S. The effects of microgravity and space radiation on cardiovascular health: From low-Earth orbit and beyond. IJC HEART & VASCULATURE 2020; 30:100595. [PMID: 32775602 PMCID: PMC7399104 DOI: 10.1016/j.ijcha.2020.100595] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 10/26/2022]
Abstract
The unique conditions of space harbor considerable challenges for astronauts to overcome. Namely, the ionizing content of space radiation and the effects of microgravity have been implicated in the pathogenesis of cardiovascular disease. Post-flight carotid arterial stiffness was demonstrated in astronaut studies while early arteriosclerosis has been linked with microgravity-induced oxidative stress in cellular studies. Similarly, radiation has been shown to disrupt molecular pathways, enhance reactive oxygen species and increase risk of cardiovascular disease in exposed populations. These results may bear even more significance in space owing to the propensity for microgravity and space radiation to yield synergistic and/or additive interactions. Potential countermeasures such as α-tocopherol and captopril target these oxidative pathways and may help to protect against the effects of microgravity and radiation-induced cardiac damage. However, more research needs to be conducted in this area to facilitate a safe passage for humans to the Moon, Mars and beyond.
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Affiliation(s)
- Smit Patel
- Vascular Biology, Cardiovascular Science, National Heart & Lung Institute (NHLI), Faculty of Medicine, Imperial College London, Dovehouse Street, London SW3 6LY, UK
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22
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Kermorgant M, Nasr N, Czosnyka M, Arvanitis DN, Hélissen O, Senard JM, Pavy-Le Traon A. Impacts of Microgravity Analogs to Spaceflight on Cerebral Autoregulation. Front Physiol 2020; 11:778. [PMID: 32719617 PMCID: PMC7350784 DOI: 10.3389/fphys.2020.00778] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
It is well known that exposure to microgravity in astronauts leads to a plethora physiological responses such as headward fluid shift, body unloading, and cardiovascular deconditioning. When astronauts return to Earth, some encounter problems related to orthostatic intolerance. An impaired cerebral autoregulation (CA), which could be compromised by the effects of microgravity, has been proposed as one of the mechanisms responsible for orthostatic intolerance. CA is a homeostatic mechanism that maintains cerebral blood flow for any variations in cerebral perfusion pressure by adapting the vascular tone and cerebral vessel diameter. The ground-based models of microgravity are useful tools for determining the gravitational impact of spaceflight on human body. The head-down tilt bed rest (HDTBR), where the subject remains in supine position at -6 degrees for periods ranging from few days to several weeks is the most commonly used ground-based model of microgravity for cardiovascular deconditioning. head-down bed rest (HDBR) is able to replicate cephalic fluid shift, immobilization, confinement, and inactivity. Dry immersion (DI) model is another approach where the subject remains immersed in thermoneutral water covered with an elastic waterproof fabric separating the subject from the water. Regarding DI, this analog imitates absence of any supporting structure for the body, centralization of body fluids, immobilization and hypokinesia observed during spaceflight. However, little is known about the impact of microgravity on CA. Here, we review the fundamental principles and the different mechanisms involved in CA. We also consider the different approaches in order to assess CA. Finally, we focus on the effects of short- and long-term spaceflight on CA and compare these findings with two specific analogs to microgravity: HDBR and DI.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospital, Cambridge, United Kingdom
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Dina N. Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Ophélie Hélissen
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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23
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Norsk P. Adaptation of the cardiovascular system to weightlessness: Surprises, paradoxes and implications for deep space missions. Acta Physiol (Oxf) 2020; 228:e13434. [PMID: 31872965 DOI: 10.1111/apha.13434] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/18/2019] [Accepted: 12/18/2019] [Indexed: 01/02/2023]
Abstract
Weightlessness in space induces a fluid shift from the dependent to the cephalad parts of the body leading to distension of the cardiac chambers and an accumulation of blood in the veins of the head and neck. Surprisingly, central venous pressure (CVP) during the initial hours of spaceflight decreases compared to being horizontal supine on the ground. The explanation is that the thorax is expanded by weightlessness leading to a decrease in inter-pleural pressure (IPP), which exceeds the measured decrease in CVP. Thus, transmural CVP (TCVP = CVP - IPP) is increased indicating an augmented cardiac preload. Simultaneously, stroke volume and cardiac output (CO) are increased by 18%-26% within the initial weeks and more so by 35%-56% during the subsequent months of flight relative to in the upright posture on the ground. Mean arterial pressure (MAP) is decreased indicating a lower systemic vascular resistance (MAP/CO). It is therefore a surprise that sympathetic nerve activity is not suppressed in space and thus cannot be a mechanism for the systemic vasodilation, which still needs to be explored. Recent observations indicate that the fluid shift during long duration (months) flights is associated with increased retinal thickness that sometimes leads to optical disc oedema. Ocular and cerebral structural changes, increases in left atrial size and decreased flows with thrombi formation in the left internal jugular vein have also been observed. This is of concern for future long duration deep space missions because the health implications are unknown.
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Affiliation(s)
- Peter Norsk
- Center for Space Medicine & Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston TX USA
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24
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25
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Wood KN, Murray KR, Greaves DK, Hughson RL. Inflight leg cuff test does not identify the risk for orthostatic hypotension after long-duration spaceflight. NPJ Microgravity 2019; 5:22. [PMID: 31633009 PMCID: PMC6789148 DOI: 10.1038/s41526-019-0082-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 09/18/2019] [Indexed: 11/09/2022] Open
Abstract
Landing day symptoms from orthostatic hypotension after prolonged spaceflight can be debilitating, but severity of these symptoms can be unpredictable and highly individual. We tested the hypothesis that an impaired baroreflex response to an inflight leg cuff test could predict orthostatic intolerance on return to Earth. Eight male astronauts (44 ± 7 years of age (mean ± SD); mean mission length: 167 ± 12 days) participated in a standardized supine-to-sit-to-stand test (5 min-30s-3 min) pre- and postflight, and a 3 min thigh cuff occlusion test pre- and inflight with continuous monitoring of heart rate and arterial blood pressure. The arterial baroreflex was not changed inflight as shown by similar reductions in mean arterial pressure (MAP) response to leg cuff deflation (preflight -19 ± 2 mmHg vs. inflight -18 ± 5 mmHg). With the sit/stand test, the nadir of MAP was lower postflight (-17 ± 9 mmHg) than preflight (-11 ± 6 mmHg, p < 0.05). A greater increase in heart rate (25 ± 7; 16 ± 3 bpm) and decrease in stroke volume (-24 ± 11; -6 ± 4 mL) occurred with sit/stand postflight than leg cuffs inflight (p < 0.001). Inflight testing was influenced by elevated cardiac output resulting in a smaller drop in total peripheral resistance. Two of eight subjects exhibited orthostatic hypotension during the postflight stand test; their responses were not predicted by the inflight leg cuff deflation test. These results suggest that the baroreflex response examined by inflight leg cuff deflation was not a reliable indicator of postflight stand responses.
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Affiliation(s)
- Katelyn N Wood
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON Canada
| | - Kevin R Murray
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON Canada
| | - Danielle K Greaves
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON Canada
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26
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Fu Q, Shibata S, Hastings JL, Platts SH, Hamilton DM, Bungo MW, Stenger MB, Ribeiro C, Adams-Huet B, Levine BD. Impact of Prolonged Spaceflight on Orthostatic Tolerance During Ambulation and Blood Pressure Profiles in Astronauts. Circulation 2019; 140:729-738. [DOI: 10.1161/circulationaha.119.041050] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Background:
Astronauts returning to earth usually demonstrate reduced orthostatic tolerance when assessed on a tilt table or quiet standing, but no studies have evaluated postflight orthostatic tolerance during activities of daily living, when it is most clinically relevant. Ambulatory blood pressure (BP) variability also is associated with orthostatic intolerance in certain patient populations and can capture clinically significant orthostatic hypotension during activities of daily living, especially when measured on a beat-to-beat basis. We evaluated the impact of prolonged spaceflight on orthostatic tolerance and BP profiles in astronauts.
Methods:
Ambulatory beat-to-beat BP was recorded using a portable device for multiple 24-hour time periods before, during, and after 6 months of spaceflight in 12 astronauts (4 women; age 48±5 [mean±SD] years). BP variability in the time domain was calculated as the SD. Systolic BP distribution during activities of daily living was characterized by skewness and kurtosis.
Results:
In contrast with results from previous studies that used tilt tables or stand tests, no astronaut experienced orthostatic intolerance/hypotension during activities of daily living before or after spaceflight. Also, 24-hour systolic BP decreased in space (120±10 mm Hg before spaceflight versus 106±9 mm Hg during spaceflight;
P
<0.01), but it returned to normal upon landing (122±13 mm Hg). Diastolic BP was unchanged during and after spaceflight. Systolic and diastolic BP variability remained the same before, during, and after spaceflight (both
P
>0.05). The skewness of systolic BP increased in space (0.74±0.51 versus 1.43±1.00;
P
=0.001), indicating that signal fluctuations became asymmetrical; however, it returned to preflight levels after landing (0.51±0.42). The kurtosis increased in space (5.01±7.67 versus 11.10±11.79;
P
=0.010), suggesting that fluctuations concentrated around the mean with a narrow distribution; however, it also returned to preflight levels (2.21±2.56) after return to earth.
Conclusions:
Given current countermeasures including in-flight exercise training and volume resuscitation on return, no astronauts experienced orthostatic hypotension or intolerance during routine (for landing day) activities in the initial 24 hours after landing following 6 months in space. Prolonged exposure to spaceflight had little impact on systolic BP variability and its distribution, although the latter showed a transient change in space (accompanied by mild relative hypotension), all of which returned to preflight values after return to earth.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (Q.F., S.S., B.D.L.)
- The University of Texas Southwestern Medical Center, Dallas (Q.F., S.S., J.L.H., B.A.-H., B.D.L.)
| | - Shigeki Shibata
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (Q.F., S.S., B.D.L.)
- The University of Texas Southwestern Medical Center, Dallas (Q.F., S.S., J.L.H., B.A.-H., B.D.L.)
| | - Jeffrey L. Hastings
- The University of Texas Southwestern Medical Center, Dallas (Q.F., S.S., J.L.H., B.A.-H., B.D.L.)
| | - Steven H. Platts
- NASA Johnson Space Center, Houston, TX (S.H.P., D.M.H., M.B.S., C.R.)
| | - Douglas M. Hamilton
- NASA Johnson Space Center, Houston, TX (S.H.P., D.M.H., M.B.S., C.R.)
- The University of Calgary, Alberta, Canada (D.M.H.)
| | - Michael W. Bungo
- The University of Texas McGovern Medical School, Houston (M.W.B.)
| | | | - Christine Ribeiro
- NASA Johnson Space Center, Houston, TX (S.H.P., D.M.H., M.B.S., C.R.)
| | - Beverley Adams-Huet
- The University of Texas Southwestern Medical Center, Dallas (Q.F., S.S., J.L.H., B.A.-H., B.D.L.)
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas (Q.F., S.S., B.D.L.)
- The University of Texas Southwestern Medical Center, Dallas (Q.F., S.S., J.L.H., B.A.-H., B.D.L.)
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27
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Barbic F, Heusser K, Minonzio M, Shiffer D, Cairo B, Tank J, Jordan J, Diedrich A, Gauger P, Zamuner RA, Porta A, Furlan R. Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals. Front Physiol 2019; 10:1061. [PMID: 31507438 PMCID: PMC6716544 DOI: 10.3389/fphys.2019.01061] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 08/02/2019] [Indexed: 11/13/2022] Open
Abstract
Orthostatic intolerance commonly occurs after prolonged bed rest, thus increasing the risk of syncope and falls. Baroreflex-mediated adjustments of heart rate and sympathetic vasomotor activity (muscle sympathetic nerve activity – MSNA) are crucial for orthostatic tolerance. We hypothesized that prolonged bed rest deconditioning alters overall baroreceptor functioning, thereby reducing orthostatic tolerance in healthy volunteers. As part of the European Space Agency Medium-term Bed Rest protocol, 10 volunteers were studied before and after 21 days of −6° head down bed rest (HDBR). In both conditions, subjects underwent ECG, beat-by-beat blood pressure, respiratory activity, and MSNA recordings while supine (REST) and during a 15-min 80° head-up tilt (TILT) followed by a 3-min −10 mmHg stepwise increase of lower body negative pressure to pre-syncope. Cardiac baroreflex sensitivity (cBRS) was obtained in the time (sequence method) and frequency domain (spectrum and cross-spectrum analyses of RR interval and systolic arterial pressure – SAP, variability). Baroreceptor modulation of sympathetic discharge activity to the vessels (sBRS) was estimated by the slope of the regression line between the percentage of MSNA burst occurrence and diastolic arterial pressure. Orthostatic tolerance significantly decreased after HDBR (12 ± 0.6 min) compared to before (21 ± 0.6 min). While supine, heart rate, SAP, and cBRS were unchanged before and after HDBR, sBRS gain was slightly depressed after than before HDBR (sBRS: −6.0 ± 1.1 versus −2.9 ± 1.5 burst% × mmHg−1, respectively). During TILT, HR was higher after than before HDBR (116 ± 4 b/min versus 100 ± 4 b/min, respectively), SAP was unmodified in both conditions, and cBRS indexes were lower after HDBR (α index: 3.4 ± 0.7 ms/mmHg; BRSSEQ 4.0 ± 1.0) than before (α index: 6.4 ± 1.0 ms/mmHg; BRSSEQ 6.8 ± 1.2). sBRS gain was significantly more depressed after HDBR than before (sBRS: −2.3 ± 0.7 versus −4.4 ± 0.4 burst% × mmHg−1, respectively). Our findings suggest that baroreflex-mediated adjustments in heart rate and MSNA are impaired after prolonged bed rest. The mechanism likely contributes to the decrease in orthostatic tolerance.
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Affiliation(s)
- Franca Barbic
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Karsten Heusser
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Maura Minonzio
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Dana Shiffer
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Jens Tank
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - André Diedrich
- Autonomic Dysfunction Center, Clinical Research Center (CRC), Department of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Peter Gauger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | | | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Policlinico di San Donato, San Donato Milanese, Italy
| | - Raffaello Furlan
- Humanitas Clinical and Research Center, Department of Internal Medicine, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Humanitas University, Rozzano, Italy
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28
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Goswami N, Blaber AP, Hinghofer-Szalkay H, Convertino VA. Lower Body Negative Pressure: Physiological Effects, Applications, and Implementation. Physiol Rev 2019; 99:807-851. [PMID: 30540225 DOI: 10.1152/physrev.00006.2018] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
This review presents lower body negative pressure (LBNP) as a unique tool to investigate the physiology of integrated systemic compensatory responses to altered hemodynamic patterns during conditions of central hypovolemia in humans. An early review published in Physiological Reviews over 40 yr ago (Wolthuis et al. Physiol Rev 54: 566-595, 1974) focused on the use of LBNP as a tool to study effects of central hypovolemia, while more than a decade ago a review appeared that focused on LBNP as a model of hemorrhagic shock (Cooke et al. J Appl Physiol (1985) 96: 1249-1261, 2004). Since then there has been a great deal of new research that has applied LBNP to investigate complex physiological responses to a variety of challenges including orthostasis, hemorrhage, and other important stressors seen in humans such as microgravity encountered during spaceflight. The LBNP stimulus has provided novel insights into the physiology underlying areas such as intolerance to reduced central blood volume, sex differences concerning blood pressure regulation, autonomic dysfunctions, adaptations to exercise training, and effects of space flight. Furthermore, approaching cardiovascular assessment using prediction models for orthostatic capacity in healthy populations, derived from LBNP tolerance protocols, has provided important insights into the mechanisms of orthostatic hypotension and central hypovolemia, especially in some patient populations as well as in healthy subjects. This review also presents a concise discussion of mathematical modeling regarding compensatory responses induced by LBNP. Given the diverse applications of LBNP, it is to be expected that new and innovative applications of LBNP will be developed to explore the complex physiological mechanisms that underline health and disease.
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Affiliation(s)
- Nandu Goswami
- Physiology Section, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz , Graz , Austria ; Department of Biomedical Physiology and Kinesiology, Simon Fraser University , Burnaby, British Columbia , Canada ; Battlefield Health & Trauma Center for Human Integrative Physiology, Combat Casualty Care Research Program, US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Andrew Philip Blaber
- Physiology Section, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz , Graz , Austria ; Department of Biomedical Physiology and Kinesiology, Simon Fraser University , Burnaby, British Columbia , Canada ; Battlefield Health & Trauma Center for Human Integrative Physiology, Combat Casualty Care Research Program, US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Helmut Hinghofer-Szalkay
- Physiology Section, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz , Graz , Austria ; Department of Biomedical Physiology and Kinesiology, Simon Fraser University , Burnaby, British Columbia , Canada ; Battlefield Health & Trauma Center for Human Integrative Physiology, Combat Casualty Care Research Program, US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Victor A Convertino
- Physiology Section, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz , Graz , Austria ; Department of Biomedical Physiology and Kinesiology, Simon Fraser University , Burnaby, British Columbia , Canada ; Battlefield Health & Trauma Center for Human Integrative Physiology, Combat Casualty Care Research Program, US Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
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29
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Carter JR. Microneurography and sympathetic nerve activity: a decade-by-decade journey across 50 years. J Neurophysiol 2019; 121:1183-1194. [PMID: 30673363 DOI: 10.1152/jn.00570.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The technique of microneurography has advanced the field of neuroscience for the past 50 years. While there have been a number of reviews on microneurography, this paper takes an objective approach to exploring the impact of microneurography studies. Briefly, Web of Science (Thomson Reuters) was used to identify the highest citation articles over the past 50 years, and key findings are presented in a decade-by-decade highlight. This includes the establishment of microneurography in the 1960s, the acceleration of the technique by Gunnar Wallin in the 1970s, the international collaborations of the 1980s and 1990s, and finally the highest impact studies from 2000 to present. This journey through 50 years of microneurographic research related to peripheral sympathetic nerve activity includes a historical context for several of the laboratory interventions commonly used today (e.g., cold pressor test, mental stress, lower body negative pressure, isometric handgrip, etc.) and how these interventions and experimental approaches have advanced our knowledge of cardiovascular, cardiometabolic, and other human diseases and conditions.
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Affiliation(s)
- Jason R Carter
- Department of Kinesiology and Integrative Physiology, Michigan Technological University , Houghton, Michigan
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30
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Abstract
In the first section, this historical review describes endeavors to develop the method for recording normal nerve impulse traffic in humans, designated microneurography. The method was developed at the Department of Clinical Neurophysiology of the Academic Hospital in Uppsala, Sweden. Microneurography involves the impalement of a peripheral nerve with a tungsten needle electrode. Electrode position is adjusted by hand until the activity of interest is discriminated. Nothing similar had previously been tried in animal preparations, and thus the large number of preceding studies that recorded afferent activity in other mammals did not offer pertinent methodological guidance. For 2 years, the two scientists involved in the research impaled their own nerves with electrodes to test various kinds of needles and explore different neural systems, all the while carefully watching for signs of nerve damage. Temporary paresthesiae were common, whereas enduring sequelae never followed. Single-unit impulse trains could be discriminated, even those originating from unmyelinated fibers. An explanation for the discrimination of unitary impulses using a coarse electrode is inferred based on the electrical characteristics of the electrode placed in the flesh and the impulse shapes, as discussed in the second section of this paper. Microneurography and the microstimulation of single afferents, combined with psychophysical methods and behavioral tests, have generated new knowledge particularly regarding four neural systems, namely the proprioceptive system, the cutaneous mechanoreceptive system, the cutaneous nociceptive system, and the sympathetic efferent system to skin structures and muscular blood vessels. Examples of achievements based on microneurography are presented in the final section.
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Affiliation(s)
- Åke Bernhard Vallbo
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
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31
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Evans JM, Knapp CF, Goswami N. Artificial Gravity as a Countermeasure to the Cardiovascular Deconditioning of Spaceflight: Gender Perspectives. Front Physiol 2018; 9:716. [PMID: 30034341 PMCID: PMC6043777 DOI: 10.3389/fphys.2018.00716] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/24/2018] [Indexed: 12/11/2022] Open
Abstract
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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Affiliation(s)
- Joyce M. Evans
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, United States
| | - Charles F. Knapp
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY, United States
| | - Nandu Goswami
- Physiology, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz, Graz, Austria
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Klassen SA, De Abreu S, Greaves DK, Kimmerly DS, Arbeille P, Denise P, Hughson RL, Normand H, Shoemaker JK. Long-duration bed rest modifies sympathetic neural recruitment strategies in male and female participants. J Appl Physiol (1985) 2018; 124:769-779. [PMID: 29212669 PMCID: PMC5899270 DOI: 10.1152/japplphysiol.00640.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 11/09/2017] [Accepted: 12/04/2017] [Indexed: 01/07/2023] Open
Abstract
To understand the impact of physical deconditioning with head-down tilt bed rest (HDBR) on the malleability of sympathetic discharge patterns, we studied 1) baseline integrated muscle sympathetic nerve activity (MSNA; microneurography) from 13 female participants in the WISE-2005 60-day HDBR study (retrospective analysis), 2) integrated MSNA and multiunit action potential (AP) analysis in 13 male participants performed on data collected at baseline and during physiological stress imposed by end-inspiratory apnea in a new 60-day HDBR study, and 3) a repeatability study (control; n = 6, retrospective analysis, 4 wk between tests). Neither baseline integrated burst frequency nor incidence were altered with HDBR (both P > 0.35). However, baseline integrated burst latency increased in both HDBR studies (male: 1.35 ± 0.02 to 1.39 ± 0.02 s, P < 0.01; female: 1.23 ± 0.02 to 1.29 ± 0.02 s, P < 0.01), whereas controls exhibited no change across two visits (1.25 ± 0.02 to 1.25 ± 0.02 s, group-by-time interaction, P = 0.02). With the exception of increased AP latency ( P = 0.03), male baseline AP data did not change with HDBR (all P > 0.19). The change in AP frequency on going from baseline to apnea (∆94 ± 25 to ∆317 ± 55 AP/min, P < 0.01) and the number of active sympathetic clusters per burst (∆0 ± 0.2 to ∆1 ± 0.2 clusters/burst, P = 0.02) were greater post- compared with pre-HDBR. The change in total clusters with apnea was ∆0 ± 0.5 clusters pre- and ∆2 ± 0.7 clusters post-HDBR ( P = 0.07). These data indicate that 60-day HDBR modified discharge characteristics in baseline burst latency and sympathetic neural recruitment during apneic stress. NEW & NOTEWORTHY Long-duration bed rest did not modify baseline sympathetic burst frequency in male and female participants, but examination of additional features of the multiunit signal provided novel evidence to suggest augmented synaptic delays or processing times at baseline for all sympathetic action potentials. Furthermore, long-duration bed rest increased reflex-sympathetic arousal to apneic stress in male participants primarily by mechanisms involving an augmented firing rate of action potential clusters active at baseline.
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Affiliation(s)
- Stephen A Klassen
- Neurovascular Research Laboratory, School of Kinesiology, University of Western Ontario , London, Ontario , Canada
| | | | - Danielle K Greaves
- Schlegel-University of Waterloo Research Institute for Aging , Waterloo, Ontario , Canada
| | - Derek S Kimmerly
- Division of Kinesiology, School of Health and Human Performance, Dalhousie University , Halifax, Nova Scotia , Canada
| | - Philippe Arbeille
- UMPS-CERCOM, School of Medicine, University of Tours , Tours , France
| | - Pierre Denise
- Normandie Université, Unicaen, INSERM, Caen , France
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging , Waterloo, Ontario , Canada
| | - Hervé Normand
- Normandie Université, Unicaen, INSERM, Caen , France
| | - J Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, University of Western Ontario , London, Ontario , Canada
- Department of Physiology and Pharmacology, University of Western Ontario , London, Ontario , Canada
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Kawao N, Morita H, Obata K, Tamura Y, Okumoto K, Kaji H. The vestibular system is critical for the changes in muscle and bone induced by hypergravity in mice. Physiol Rep 2017; 4:4/19/e12979. [PMID: 27697847 PMCID: PMC5064136 DOI: 10.14814/phy2.12979] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 08/29/2016] [Indexed: 12/14/2022] Open
Abstract
Gravity changes concurrently affect muscle and bone as well as induce alterations in vestibular signals. However, the role of vestibular signals in the changes in muscle and bone induced by gravity changes remains unknown. We therefore investigated the effects of vestibular lesions (VL) on the changes in muscle and bone induced by 3 g hypergravity for 4 weeks in C57BL/6J mice. Quantitative computed tomography analysis revealed that hypergravity increased muscle mass surrounding the tibia and trabecular bone mineral content, adjusting for body weight in mice. Hypergravity did not affect cortical bone and fat masses surrounding the tibia. Vestibular lesions blunted the increases in muscle and bone masses induced by hypergravity. Histological analysis showed that hypergravity elevated the cross‐sectional area of myofiber in the soleus muscle. The mRNA levels of myogenic genes such as MyoD, Myf6, and myogenin in the soleus muscle were elevated in mice exposed to hypergravity. Vestibular lesions attenuated myofiber size and the mRNA levels of myogenic differentiation markers enhanced by hypergravity in the soleus muscle. Propranolol, a β‐blocker, antagonized the changes in muscle induced by hypergravity. In conclusion, this study is the first to demonstrate that gravity changes affect muscle and bone through vestibular signals and subsequent sympathetic outflow in mice.
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Affiliation(s)
- Naoyuki Kawao
- Department of Physiology and Regenerative Medicine, Kindai University Faculty of Medicine, Osakasayama, Japan
| | - Hironobu Morita
- Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan Mouse Epigenetics Project, ISS/Kibo Experiment, Japan Aerospace Exploration Agency, Tsukuba, Japan
| | - Koji Obata
- Department of Physiology, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yukinori Tamura
- Department of Physiology and Regenerative Medicine, Kindai University Faculty of Medicine, Osakasayama, Japan
| | - Katsumi Okumoto
- Life Science Research Institute, Kindai University, Osakasayama, Japan
| | - Hiroshi Kaji
- Department of Physiology and Regenerative Medicine, Kindai University Faculty of Medicine, Osakasayama, Japan
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Abstract
National space agencies and private corporations aim at an extended presence of humans in space in the medium to long term. Together with currently suboptimal technology, microgravity and cosmic rays raise health concerns about deep-space exploration missions. Both of these physical factors affect the cardiovascular system, whose gravity-dependence is pronounced. Heart and vascular function are, therefore, susceptible to substantial changes in weightlessness. The altered cardiovascular function in space causes physiological problems in the postflight period. A compromised cardiovascular system can be excessively vulnerable to space radiation, synergistically resulting in increased damage. The space radiation dose is significantly lower than in patients undergoing radiotherapy, in whom cardiac damage is well-documented following cancer therapy in the thoracic region. Nevertheless, epidemiological findings suggest an increased risk of late cardiovascular disease even with low doses of radiation. Moreover, the peculiar biological effectiveness of heavy ions in cosmic rays might increase this risk substantially. However, whether radiation-induced cardiovascular effects have a threshold at low doses is still unclear. The main countermeasures to mitigate the effect of the space environment on cardiac function are physical exercise, antioxidants, nutraceuticals, and radiation shielding.
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Otsuka K, Cornelissen G, Furukawa S, Kubo Y, Hayashi M, Shibata K, Mizuno K, Aiba T, Ohshima H, Mukai C. Long-term exposure to space's microgravity alters the time structure of heart rate variability of astronauts. Heliyon 2016; 2:e00211. [PMID: 28050606 PMCID: PMC5192238 DOI: 10.1016/j.heliyon.2016.e00211] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 11/21/2016] [Accepted: 12/05/2016] [Indexed: 01/20/2023] Open
Abstract
Background Spaceflight alters human cardiovascular dynamics. The less negative slope of the fractal scaling of heart rate variability (HRV) of astronauts exposed long-term to microgravity reflects cardiovascular deconditioning. We here focus on specific frequency regions of HRV. Methods Ten healthy astronauts (8 men, 49.1 ± 4.2 years) provided five 24-hour electrocardiographic (ECG) records: before launch, 20.8 ± 2.9 (ISS01), 72.5 ± 3.9 (ISS02) and 152.8 ± 16.1 (ISS03) days after launch, and after return to Earth. HRV endpoints, determined from normal-to-normal (NN) intervals in 180-min intervals progressively displaced by 5 min, were compared in space versus Earth. They were fitted with a model including 4 major anticipated components with periods of 24 (circadian), 12 (circasemidian), 8 (circaoctohoran), and 1.5 (Basic Rest-Activity Cycle; BRAC) hours. Findings The 24-, 12-, and 8-hour components of HRV persisted during long-term spaceflight. The 90-min amplitude became about three times larger in space (ISS03) than on Earth, notably in a subgroup of 7 astronauts who presented with a different HRV profile before flight. The total spectral power (TF; p < 0.05) and that in the ultra-low frequency range (ULF, 0.0001–0.003 Hz; p < 0.01) increased from 154.9 ± 105.0 and 117.9 ± 57.5 msec2 (before flight) to 532.7 ± 301.3 and 442.4 ± 202.9 msec2 (ISS03), respectively. The power-law fractal scaling β was altered in space, changing from -1.087 ± 0.130 (before flight) to -0.977 ± 0.098 (ISS01), -0.910 ± 0.130 (ISS02), and -0.924 ± 0.095 (ISS03) (invariably p < 0.05). Interpretation Most HRV changes observed in space relate to a frequency window centered around one cycle in about 90 min. Since the BRAC component is amplified in space for only specific HRV endpoints, it is likely to represent a physiologic response rather than an artifact from the International Space Station (ISS) orbit. If so, it may offer a way to help adaptation to microgravity during long-duration spaceflight.
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Affiliation(s)
- Kuniaki Otsuka
- Executive Medical Center, Totsuka Royal Clinic, Tokyo Women's Medical University, Tokyo, Japan; Halberg Chronobiology Center, University of Minnesota, Minneapolis, MN, USA
| | | | - Satoshi Furukawa
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
| | - Yutaka Kubo
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Mitsutoshi Hayashi
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Koichi Shibata
- Department of Medicine, Tokyo Women's Medical University, Medical Center East, Tokyo, Japan
| | - Koh Mizuno
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan; Faculty of Child and Family Studies, Tohoku Fukushi University, Miyagi, Japan
| | - Tatsuya Aiba
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan; Ministry of Education, Culture, Sports, Science and Technology, Tokyo, Japan
| | - Hiroshi Ohshima
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
| | - Chiaki Mukai
- Space Biomedical Research Group, Japan Aerospace Exploration Agency, Tokyo, Japan
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Eckberg DL, Cooke WH, Diedrich A, Biaggioni I, Buckey JC, Pawelczyk JA, Ertl AC, Cox JF, Kuusela TA, Tahvanainen KUO, Mano T, Iwase S, Baisch FJ, Levine BD, Adams-Huet B, Robertson D, Blomqvist CG. Respiratory modulation of human autonomic function on Earth. J Physiol 2016; 594:5611-27. [PMID: 27028958 PMCID: PMC5043049 DOI: 10.1113/jp271654] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/14/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We studied healthy supine astronauts on Earth with electrocardiogram, non-invasive arterial pressure, respiratory carbon dioxide concentrations, breathing depth and sympathetic nerve recordings. The null hypotheses were that heart beat interval fluctuations at usual breathing frequencies are baroreflex mediated, that they persist during apnoea, and that autonomic responses to apnoea result from changes of chemoreceptor, baroreceptor or lung stretch receptor inputs. R-R interval fluctuations at usual breathing frequencies are unlikely to be baroreflex mediated, and disappear during apnoea. The subjects' responses to apnoea could not be attributed to changes of central chemoreceptor activity (hypocapnia prevailed); altered arterial baroreceptor input (vagal baroreflex gain declined and muscle sympathetic nerve burst areas, frequencies and probabilities increased, even as arterial pressure climbed to new levels); or altered pulmonary stretch receptor activity (major breathing frequency and tidal volume changes did not alter vagal tone or sympathetic activity). Apnoea responses of healthy subjects may result from changes of central respiratory motoneurone activity. ABSTRACT We studied eight healthy, supine astronauts on Earth, who followed a simple protocol: they breathed at fixed or random frequencies, hyperventilated and then stopped breathing, as a means to modulate and expose to view important, but obscure central neurophysiological mechanisms. Our recordings included the electrocardiogram, finger photoplethysmographic arterial pressure, tidal volume, respiratory carbon dioxide concentrations and peroneal nerve muscle sympathetic activity. Arterial pressure, vagal tone and muscle sympathetic outflow were comparable during spontaneous and controlled-frequency breathing. Compared with spontaneous, 0.1 and 0.05 Hz breathing, however, breathing at usual frequencies (∼0.25 Hz) lowered arterial baroreflex gain, and provoked smaller arterial pressure and R-R interval fluctuations, which were separated by intervals that were likely to be too short and variable to be attributed to baroreflex physiology. R-R interval fluctuations at usual breathing frequencies disappear during apnoea, and thus cannot provide evidence for the existence of a central respiratory oscillation. Apnoea sets in motion a continuous and ever changing reorganization of the relations among stimulatory and inhibitory inputs and autonomic outputs, which, in our study, could not be attributed to altered chemoreceptor, baroreceptor, or pulmonary stretch receptor activity. We suggest that responses of healthy subjects to apnoea are driven importantly, and possibly prepotently, by changes of central respiratory motoneurone activity. The companion article extends these observations and asks the question, Might terrestrial responses to our 20 min breathing protocol find expression as long-term neuroplasticity in serial measurements made over 20 days during and following space travel?
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Affiliation(s)
- Dwain L Eckberg
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs, Medical Center and Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
| | - William H Cooke
- Department of Kinesiology, Health, and Nutrition, University of Texas at San Antonio, San Antonio, TX, USA
| | - André Diedrich
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Italo Biaggioni
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Jay C Buckey
- Dartmouth Hitchcock Medical Center, Lebanon, NH, USA
| | - James A Pawelczyk
- Department of Physiology, Pennsylvania State University, University Park and Hershey, PA, USA
| | - Andrew C Ertl
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - James F Cox
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs, Medical Center and Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Tom A Kuusela
- Department of Physics, University of Turku, Turku, Finland
| | - Kari U O Tahvanainen
- Department of Clinical Physiology and Nuclear Medicine, South Karelia Central Hospital, Lappeenranta, Finland
| | - Tadaaki Mano
- Gifu University of Medical Science, 795-1 Nagamine Ichihiraga, Seki, Gifu, 501-3892, Japan
| | - Satoshi Iwase
- Department of Physiology, Aichi Medical University, Aichi, Japan
| | | | - Benjamin D Levine
- Department of Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA
| | | | - David Robertson
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - C Gunnar Blomqvist
- Department of Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
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Hughes JM, Charkoudian N, Barnes JN, Morgan BJ. Revisiting the Debate: Does Exercise Build Strong Bones in the Mature and Senescent Skeleton? Front Physiol 2016; 7:369. [PMID: 27679578 PMCID: PMC5020082 DOI: 10.3389/fphys.2016.00369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/10/2016] [Indexed: 12/18/2022] Open
Abstract
Traditional exercise programs seem to be less osteogenic in the mature and post-mature skeleton compared to the young skeleton. This is likely because of the decline in sensitivity of bone to mechanical loading that occurs with advancing age. Another factor contributing to the apparently diminished benefit of exercise in older adults is failure of widely used measurement techniques (i.e., DXA) to identify changes in 3-dimensional bone structure, which are important determinants of bone strength. Moreover, although hormonal contributors to bone loss in the elderly are well-recognized, the influence of age-related increases in sympathetic nervous system activity, which impacts bone metabolism, is rarely considered. In this Perspective, we cite evidence from animal and human studies demonstrating anabolic effects of exercise on bone across the lifespan and we discuss theoretical considerations for designing exercise regimens to optimize bone health. We conclude with suggestions for future research that should help define the osteogenic potential of exercise in older individuals.
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Affiliation(s)
- Julie M Hughes
- Military Performance Division, US Army Research Institute of Environmental Medicine Natick, MA, USA
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine Natick, MA, USA
| | - Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison Madison, WI, USA
| | - Barbara J Morgan
- John Rankin Laboratory of Pulmonary Medicine, Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison Madison, WI, USA
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Eckberg DL, Diedrich A, Cooke WH, Biaggioni I, Buckey JC, Pawelczyk JA, Ertl AC, Cox JF, Kuusela TA, Tahvanainen KUO, Mano T, Iwase S, Baisch FJ, Levine BD, Adams-Huet B, Robertson D, Blomqvist CG. Respiratory modulation of human autonomic function: long-term neuroplasticity in space. J Physiol 2016; 594:5629-46. [PMID: 27029027 DOI: 10.1113/jp271656] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/14/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We studied healthy astronauts before, during and after the Neurolab Space Shuttle mission with controlled breathing and apnoea, to identify autonomic changes that might contribute to postflight orthostatic intolerance. Measurements included the electrocardiogram, finger photoplethysmographic arterial pressure, respiratory carbon dioxide levels, tidal volume and peroneal nerve muscle sympathetic activity. Arterial pressure fell and then rose in space, and drifted back to preflight levels after return to Earth. Vagal metrics changed in opposite directions: vagal baroreflex gain and two indices of vagal fluctuations rose and then fell in space, and descended to preflight levels upon return to Earth. Sympathetic burst frequencies (but not areas) were greater than preflight in space and on landing day, and astronauts' abilities to modulate both burst areas and frequencies during apnoea were sharply diminished. Spaceflight triggers long-term neuroplastic changes reflected by reciptocal sympathetic and vagal motoneurone responsiveness to breathing changes. ABSTRACT We studied six healthy astronauts five times, on Earth, in space on the first and 12th or 13th day of the 16 day Neurolab Space Shuttle mission, on landing day, and 5-6 days later. Astronauts followed a fixed protocol comprising controlled and random frequency breathing and apnoea, conceived to perturb their autonomic function and identify changes, if any, provoked by microgravity exposure. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, tidal carbon dioxide concentrations and volumes, and peroneal nerve muscle sympathetic activity on Earth (in the supine position) and in space. (Sympathetic nerve recordings were made during three sessions: preflight, late mission and landing day.) Arterial pressure changed systematically from preflight levels: pressure fell during early microgravity exposure, rose as microgravity exposure continued, and drifted back to preflight levels after return to Earth. Vagal metrics changed in opposite directions: vagal baroreflex gain and two indices of vagal fluctuations (root mean square of successive normal R-R intervals; and proportion of successive normal R-R intervals greater than 50 ms, divided by the total number of normal R-R intervals) rose significantly during early microgravity exposure, fell as microgravity exposure continued, and descended to preflight levels upon return to Earth. Sympathetic mechanisms also changed. Burst frequencies (but not areas) during fixed frequency breathing were greater than preflight in space and on landing day, but their control during apnoea was sharply altered: astronauts increased their burst frequencies from already high levels, but they could not modulate either burst areas or frequencies appropriately. Space travel provokes long-lasting sympathetic and vagal neuroplastic changes in healthy humans.
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Affiliation(s)
- Dwain L Eckberg
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
| | - André Diedrich
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - William H Cooke
- Department of Kinesiology, Health, and Nutrition, University of Texas at San Antonio, San Antonio, TX, USA
| | - Italo Biaggioni
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Jay C Buckey
- Dartmouth Hitchcock Medical Centre, Lebanon, NH, USA
| | - James A Pawelczyk
- Department of Physiology, Pennsylvania State University, University Park and Hershey, PA, USA
| | - Andrew C Ertl
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - James F Cox
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Tom A Kuusela
- Department of Physics, Turku University, Turku, Finland
| | - Kari U O Tahvanainen
- Department of Clinical Physiology and Nuclear Medicine, South Karelia Central Hospital, Lappeenranta, Finland
| | - Tadaaki Mano
- Gifu University of Medical Science, 795-1 Nagamine Ichihiraga, Seki, Gifu, 501-3892, Japan
| | - Satoshi Iwase
- Department of Physiology, Aichi Medical University, Aichi, Japan
| | | | - Benjamin D Levine
- Department of Medicine, University of Texas Southwestern Medical Centre at Dallas, Dallas, TX, USA.,Institute for Exercise and Environmental Medicine, Texas Health Presbyterian, Hospital, Dallas, TX, USA
| | | | - David Robertson
- Department of Medicine, Division of Clinical Pharmacology, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - C Gunnar Blomqvist
- Department of Medicine, University of Texas Southwestern Medical Centre at Dallas, Dallas, TX, USA
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Bloomfield SA, Martinez DA, Boudreaux RD, Mantri AV. Microgravity Stress: Bone and Connective Tissue. Compr Physiol 2016; 6:645-86. [PMID: 27065165 DOI: 10.1002/cphy.c130027] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The major alterations in bone and the dense connective tissues in humans and animals exposed to microgravity illustrate the dependency of these tissues' function on normal gravitational loading. Whether these alterations depend solely on the reduced mechanical loading of zero g or are compounded by fluid shifts, altered tissue blood flow, radiation exposure, and altered nutritional status is not yet well defined. Changes in the dense connective tissues and intervertebral disks are generally smaller in magnitude but occur more rapidly than those in mineralized bone with transitions to 0 g and during recovery once back to the loading provided by 1 g conditions. However, joint injuries are projected to occur much more often than the more catastrophic bone fracture during exploration class missions, so protecting the integrity of both tissues is important. This review focuses on the research performed over the last 20 years in humans and animals exposed to actual spaceflight, as well as on knowledge gained from pertinent ground-based models such as bed rest in humans and hindlimb unloading in rodents. Significant progress has been made in our understanding of the mechanisms for alterations in bone and connective tissues with exposure to microgravity, but intriguing questions remain to be solved, particularly with reference to biomedical risks associated with prolonged exploration missions.
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Affiliation(s)
- Susan A Bloomfield
- Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA
| | - Daniel A Martinez
- Department of Mechanical Engineering, University of Houston, Houston, Texas, USA
| | - Ramon D Boudreaux
- Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Anita V Mantri
- Department of Health & Kinesiology, Texas A&M University, College Station, Texas, USA.,Health Science Center School of Medicine, Texas A&M University, College Station, Texas, USA
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Norsk P, Asmar A, Damgaard M, Christensen NJ. Fluid shifts, vasodilatation and ambulatory blood pressure reduction during long duration spaceflight. J Physiol 2016; 593:573-84. [PMID: 25774397 DOI: 10.1113/jphysiol.2014.284869] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Weightlessness in space induces initially an increase in stroke volume and cardiac output, accompanied by unchanged or slightly reduced blood pressure.It is unclear whether these changes persist throughout months of flight.Here, we show that cardiac output and stroke volume increase by 35–41% between 3 and 6 months on the International Space Station, which is more than during shorter flights.Twenty-four hour ambulatory brachial blood pressure is reduced by 8–10 mmHg by a decrease in systemic vascular resistance of 39%, which is not a result of the suppression of sympathetic nervous activity, and the nightly dip is maintained in space.It remains a challenge to explore what causes the systemic vasodilatation leading to a reduction in blood pressure in space, and whether the unexpectedly high stroke volume and cardiac output can explain some vision acuity problems encountered by astronauts on the International Space Station. ABSTRACT Acute weightlessness in space induces a fluid shift leading to central volume expansion. Simultaneously, blood pressure is either unchanged or decreased slightly. Whether these effects persist for months in space is unclear. Twenty-four hour ambulatory brachial arterial pressures were automatically recorded at 1–2 h intervals with portable equipment in eight male astronauts: once before launch, once between 85 and 192 days in space on the International Space Station and, finally, once at least 2 months after flight. During the same 24 h, cardiac output (rebreathing method) was measured two to five times (on the ground seated), and venous blood was sampled once (also seated on the ground) for determination of plasma catecholamine concentrations. The 24 h average systolic, diastolic and mean arterial pressures (mean ± se) in space were reduced by 8 ± 2 mmHg (P = 0.01; ANOVA), 9 ± 2 mmHg (P < 0.001) and 10 ± 3 mmHg (P = 0.006), respectively. The nightly blood pressure dip of 8 ± 3 mmHg (P = 0.015) was maintained. Cardiac stroke volume and output increased by 35 ± 10% and 41 ± 9% (P < 0.001); heart rate and catecholamine concentrations were unchanged; and systemic vascular resistance was reduced by 39 ± 4% (P < 0.001). The increase in cardiac stroke volume and output is more than previously observed during short duration flights and might be a precipitator for some of the vision problems encountered by the astronauts. The spaceflight vasodilatation mechanism needs to be explored further.
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41
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Vignaux G, Ndong JD, Perrien DS, Elefteriou F. Inner Ear Vestibular Signals Regulate Bone Remodeling via the Sympathetic Nervous System. J Bone Miner Res 2015; 30:1103-11. [PMID: 25491117 PMCID: PMC4772960 DOI: 10.1002/jbmr.2426] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/01/2014] [Accepted: 12/04/2014] [Indexed: 12/23/2022]
Abstract
The inner ear vestibular system has numerous projections on central brain centers that regulate sympathetic outflow, and skeletal sympathetic projections affect bone remodeling by inhibiting bone formation by osteoblasts and promoting bone resorption by osteoclasts. In this study, we show that bilateral vestibular lesions in mice cause a low bone mass phenotype associated with decreased bone formation and increased bone resorption. This reduction in bone mass is most pronounced in lower limbs, is not associated with reduced locomotor activity or chronic inflammation, and could be prevented by the administration of the β-blocker propranolol and by genetic deletion of the β2-adrenergic receptor, globally or specifically in osteoblasts. These results provide novel experimental evidence supporting a functional autonomic link between central proprioceptive vestibular structures and the skeleton. Because vestibular dysfunction often affects the elderly, these results also suggest that age-related bone loss might have a vestibular component and that patients with inner ear pathologies might be at risk for fracture. Lastly, these data might have relevance to the bone loss observed in microgravity, as vestibular function is altered in this condition as well. © 2015 American Society for Bone and Mineral Research.
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Affiliation(s)
- Guillaume Vignaux
- Department of Medicine, Vanderbilt University Medical Center, Vanderbilt Center for Bone Biology, Nashville, TN, USA
| | - Jean Dlc Ndong
- Department of Medicine, Vanderbilt University Medical Center, Vanderbilt Center for Bone Biology, Nashville, TN, USA
| | - Daniel S Perrien
- Department of Orthopaedic Surgery & Rehabilitation/Department of VA, Vanderbilt University Medical Center, Vanderbilt Center for Bone Biology, Nashville, TN, USA
| | - Florent Elefteriou
- Department of Medicine, Vanderbilt University Medical Center, Vanderbilt Center for Bone Biology, Nashville, TN, USA
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Mandsager KT, Robertson D, Diedrich A. The function of the autonomic nervous system during spaceflight. Clin Auton Res 2015; 25:141-51. [PMID: 25820827 DOI: 10.1007/s10286-015-0285-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 01/08/2015] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Despite decades of study, a clear understanding of autonomic nervous system activity in space remains elusive. Differential interpretation of fundamental data has driven divergent theories of sympathetic activation and vasorelaxation. METHODS This paper will review the available in-flight autonomic and hemodynamic data in an effort to resolve these discrepancies. The NASA NEUROLAB mission, the most comprehensive assessment of autonomic function in microgravity to date, will be highlighted. The mechanisms responsible for altered autonomic activity during spaceflight, which include the effects of hypovolemia, cardiovascular deconditioning, and altered central processing, will be presented. RESULTS The NEUROLAB experiments demonstrated increased sympathetic activity and impairment of vagal baroreflex function during short-duration spaceflight. Subsequent non-invasive studies of autonomic function during spaceflight have largely reinforced these findings, and provide strong evidence that sympathetic activity is increased in space relative to the supine position on Earth. Others have suggested that microgravity induces a state of relative vasorelaxation and increased vagal activity when compared to upright posture on Earth. These ostensibly disparate theories are not mutually exclusive, but rather directly reflect different pre-flight postural controls. CONCLUSION When these results are taken together, they demonstrate that the effectual autonomic challenge of spaceflight is small, and represents an orthostatic stress less than that of upright posture on Earth. In-flight countermeasures, including aerobic and resistance exercise, as well short-arm centrifugation, have been successfully deployed to counteract these mechanisms. Despite subtle changes in autonomic activity during spaceflight, underlying neurohumoral mechanisms of the autonomic nervous system remain intact and cardiovascular function remains stable during long-duration flight.
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Affiliation(s)
- Kyle Timothy Mandsager
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University School of Medicine, 1161 21st Avenue South, Suite AA3228 MCN, Nashville, TN, 37232-2195, USA
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Liu J, Li Y, Verheyden B, Chen S, Chen Z, Gai Y, Liu J, Gao J, Xie Q, Yuan M, Li Q, Li L, Aubert AE. Is autonomic modulation different between European and Chinese astronauts? PLoS One 2015; 10:e0120920. [PMID: 25799561 PMCID: PMC4370477 DOI: 10.1371/journal.pone.0120920] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Accepted: 02/09/2015] [Indexed: 11/29/2022] Open
Abstract
Purpose The objective was to investigate autonomic control in groups of European and Chinese astronauts and to identify similarities and differences. Methods Beat-to-beat heart rate and finger blood pressure, brachial blood pressure, and respiratory frequency were measured from 10 astronauts (five European taking part in three different space missions and five Chinese astronauts taking part in two different space missions). Data recording was performed in the supine and standing positions at least 10 days before launch, and 1, 3, and 10 days after return. Cross-correlation analysis of heart rate and systolic pressure was used to assess cardiac baroreflex modulation. A fixed breathing protocol was performed to measure respiratory sinus arrhythmia and low-frequency power of systolic blood pressure variability. Results Although baseline cardiovascular parameters before spaceflight were similar in all astronauts in the supine position, a significant increase in sympathetic activity and a decrease in vagal modulation occurred in the European astronauts when standing; spaceflight resulted in a remarkable vagal decrease in European astronauts only. Similar baseline supine and standing values for heart rate, mean arterial pressure, and respiratory frequency were shown in both groups. Standing autonomic control was based on a balance of higher vagal and sympathetic modulation in European astronauts. Conclusion Post-spaceflight orthostatic tachycardia was observed in all European astronauts, whereas post-spaceflight orthostatic tachycardia was significantly reduced in Chinese astronauts. The basis for orthostatic intolerance is not apparent; however, many possibilities can be considered and need to be further investigated, such as genetic diversities between races, astronaut selection, training, and nutrition, etc.
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Affiliation(s)
- Jiexin Liu
- Department of Cardiology, Beijing Friendship Hospital, China Capital Medical University, Beijing, China
- Department of Cardiology, University Hospital Gasthuisberg, K. U. Leuven, Leuven, Belgium
- * E-mail: (JL); (MY)
| | | | - Bart Verheyden
- Department of Cardiology, University Hospital Gasthuisberg, K. U. Leuven, Leuven, Belgium
| | | | | | | | | | | | - Qiong Xie
- China Astronaut Center, Beijing, China
| | - Ming Yuan
- China Astronaut Center, Beijing, China
- * E-mail: (JL); (MY)
| | - Qin Li
- Department of Cardiology, Beijing Friendship Hospital, China Capital Medical University, Beijing, China
| | - Li Li
- Department of Cardiology, Beijing Friendship Hospital, China Capital Medical University, Beijing, China
| | - André E. Aubert
- Department of Cardiology, University Hospital Gasthuisberg, K. U. Leuven, Leuven, Belgium
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Hughson RL, Shoemaker JK. Autonomic responses to exercise: Deconditioning/inactivity. Auton Neurosci 2015; 188:32-5. [DOI: 10.1016/j.autneu.2014.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/13/2014] [Indexed: 12/29/2022]
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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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Blood pressure regulation IV: adaptive responses to weightlessness. Eur J Appl Physiol 2014; 114:481-97. [PMID: 24390686 DOI: 10.1007/s00421-013-2797-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/11/2013] [Indexed: 10/25/2022]
Abstract
During weightlessness, blood and fluids are immediately shifted from the lower to the upper body segments, and within the initial 2 weeks of spaceflight, brachial diastolic arterial pressure is reduced by 5 mmHg and even more so by some 10 mmHg from the first to the sixth month of flight. Blood pressure thus adapts in space to a level very similar to that of being supine on the ground. At the same time, stroke volume and cardiac output are increased and systemic vascular resistance decreased, whereas sympathetic nerve activity is kept surprisingly high and similar to when ground-based upright seated. This was not predicted from simulation models and indicates that dilatation of the arteriolar resistance vessels is caused by mechanisms other than a baroreflex-induced decrease in sympathetic nervous activity. Results of baroreflex studies in space indicate that compared to being ground-based supine, the carotid (vagal)-cardiac interaction is reduced and sympathetic nerve activity, heart rate and systemic vascular resistance response more pronounced during baroreflex inhibition by lower body negative pressure. The future challenge is to identify which spaceflight mechanism induces peripheral arteriolar dilatation, which could explain the decrease in blood pressure, the high sympathetic nerve activity and associated cardiovascular changes. It is also a challenge to determine the cardiovascular risk profile of astronauts during future long-duration deep space missions.
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Eckberg DL, Cooke WH, Diedrich A, Levine BD, Pawelczyk JA, Buckey JC, Ertl AC, Biaggioni I, Cox JF, Robertson D, Baisch FJ, Blomqvist CG, Kuusela TA, Tahvanainen KUO. Human baroreflex rhythms persist during handgrip and muscle ischaemia. Acta Physiol (Oxf) 2013; 209:114-23. [PMID: 23809494 PMCID: PMC3875341 DOI: 10.1111/apha.12143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 05/20/2013] [Accepted: 06/20/2013] [Indexed: 12/20/2022]
Abstract
AIM To determine whether physiological, rhythmic fluctuations of vagal baroreflex gain persist during exercise, post-exercise ischaemia and recovery. METHODS We studied responses of six supine healthy men and one woman to a stereotyped protocol comprising rest, handgrip exercise at 40% maximum capacity to exhaustion, post-exercise forearm ischaemia and recovery. We measured electrocardiographic R-R intervals, photoplethysmographic finger arterial pressures and peroneal nerve muscle sympathetic activity. We derived vagal baroreflex gains from a sliding (25-s window moved by 2-s steps) systolic pressure-R-R interval transfer function at 0.04-0.15 Hz. RESULTS Vagal baroreflex gain oscillated at low, nearly constant frequencies throughout the protocol (at approx. 0.06 Hz - a period of about 18 s); however, during exercise, most oscillations were at low-gain levels, and during ischaemia and recovery, most oscillations were at high-gain levels. CONCLUSIONS Vagal baroreflex rhythms are not abolished by exercise, and they are not overwhelmed after exercise during ischaemia and recovery.
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Affiliation(s)
- D. L. Eckberg
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs Medical Center and Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA
| | - W. H. Cooke
- Health and Kinesiology, University of Texas at San Antonio, San Antonio, TX, USA
| | - A. Diedrich
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN, USA
| | - B. D. Levine
- Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - J. A. Pawelczyk
- The Pennsylvania State University, University Park and Hershey, PA, USA
| | - J. C. Buckey
- Dartmouth Hitchcock Medical Center, Lebanon, NH, USA
| | - A. C. Ertl
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN, USA
| | - I. Biaggioni
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN, USA
| | - J. F. Cox
- Departments of Medicine and Physiology, Hunter Holmes McGuire Department of Veterans Affairs Medical Center and Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA
| | - D. Robertson
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN, USA
| | - F. J. Baisch
- DLR-Institute for Aerospace Medicine, Cologne, Germany
| | - C. G. Blomqvist
- Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - T. A. Kuusela
- Department of Physics, Turku University, Turku, Finland
| | - K. U. O. Tahvanainen
- Department of Clinical Physiology and Nuclear Medicine, South Karelia Central Hospital, Lappeenranta, Finland
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Messerotti Benvenuti S, Bianchin M, Angrilli A. Posture affects emotional responses: a Head Down Bed Rest and ERP study. Brain Cogn 2013; 82:313-8. [PMID: 23792473 DOI: 10.1016/j.bandc.2013.05.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 04/23/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
Abstract
Body posture, mainly represented by horizontal bed rest, has been found to be associated with cortical inhibition, altered perceptual and cognitive processing. In the present research, the influence of Head Down Bed Rest (HDBR)--a condition also termed simulated microgravity--on emotional responses has been studied. Twenty-two male subjects were randomly assigned to either Sitting Control or HDBR group. After 3-h, subjects attended to a passive viewing emotional task in which 75 IAPS slides, divided into 25 pleasant, 25 neutral and 25 unpleasant, were presented in random order for 6s each, while EEG was recorded from F7, F8 and Pz locations. Results showed in Sitting Controls the expected greater P300 and Late Positive Potential (LPP) to pleasant and unpleasant compared with neutral slides, an effect which indicates greater processing of emotional arousing stimuli. The HDBR group showed smaller non-significant differences among all emotional conditions in both ERP components. Arousal and valence subjective evaluations, typically less sensitive to experimental manipulation, did not differentiate groups. The observed ability of HDBR to inhibit cortical emotional responses raises an important issue on the risk that astronauts underestimate a dangerous/threatening situation or that long-term bedridden inpatients develop depressive symptoms.
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Zhang LF. Region-specific vascular remodeling and its prevention by artificial gravity in weightless environment. Eur J Appl Physiol 2013; 113:2873-95. [DOI: 10.1007/s00421-013-2597-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
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Arzeno NM, Stenger MB, Lee SMC, Ploutz-Snyder R, Platts SH. Sex differences in blood pressure control during 6° head-down tilt bed rest. Am J Physiol Heart Circ Physiol 2013; 304:H1114-23. [PMID: 23396455 DOI: 10.1152/ajpheart.00391.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spaceflight-induced orthostatic intolerance has been studied for decades. Although ∼22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps.
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Affiliation(s)
- Natalia M Arzeno
- Wyle Science, Technology and Engineering Group, Houston, Texas, USA
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