1
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Han H, Jia H, Wang YF, Song JP. Cardiovascular adaptations and pathological changes induced by spaceflight: from cellular mechanisms to organ-level impacts. Mil Med Res 2024; 11:68. [PMID: 39334239 PMCID: PMC11429428 DOI: 10.1186/s40779-024-00570-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 09/01/2024] [Indexed: 09/30/2024] Open
Abstract
The advancement in extraterrestrial exploration has highlighted the crucial need for studying how the human cardiovascular system adapts to space conditions. Human development occurs under the influence of gravity, shielded from space radiation by Earth's magnetic field, and within an environment characterized by 24-hour day-night cycles resulting from Earth's rotation, thus deviating from these conditions necessitates adaptive responses for survival. With upcoming manned lunar and Martian missions approaching rapidly, it is essential to understand the impact of various stressors induced by outer-space environments on cardiovascular health. This comprehensive review integrates insights from both actual space missions and simulated experiments on Earth, to analyze how microgravity, space radiation, and disrupted circadian affect cardiovascular well-being. Prolonged exposure to microgravity induces myocardial atrophy and endothelial dysfunction, which may be exacerbated by space radiation. Mitochondrial dysfunction and oxidative stress emerge as key underlying mechanisms along with disturbances in ion channel perturbations, cytoskeletal damage, and myofibril changes. Disruptions in circadian rhythms caused by factors such as microgravity, light exposure, and irregular work schedules, could further exacerbate cardiovascular issues. However, current research tends to predominantly focus on disruptions in the core clock gene, overlooking the multifactorial nature of circadian rhythm disturbances in space. Future space missions should prioritize targeted prevention strategies and early detection methods for identifying cardiovascular risks, to preserve astronaut health and ensure mission success.
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Affiliation(s)
- Han Han
- Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Animal Experimental Centre, National Centre for Cardiovascular Disease; Department of Cardiac Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Hao Jia
- Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Animal Experimental Centre, National Centre for Cardiovascular Disease; Department of Cardiac Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Yi-Fan Wang
- Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Animal Experimental Centre, National Centre for Cardiovascular Disease; Department of Cardiac Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Jiang-Ping Song
- Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Animal Experimental Centre, National Centre for Cardiovascular Disease; Department of Cardiac Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China.
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2
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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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3
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Costello HM, Johnston JG, Juffre A, Crislip GR, Gumz ML. Circadian clocks of the kidney: function, mechanism, and regulation. Physiol Rev 2022; 102:1669-1701. [PMID: 35575250 PMCID: PMC9273266 DOI: 10.1152/physrev.00045.2021] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 05/03/2022] [Accepted: 05/07/2022] [Indexed: 11/22/2022] Open
Abstract
An intrinsic cellular circadian clock is located in nearly every cell of the body. The peripheral circadian clocks within the cells of the kidney contribute to the regulation of a variety of renal processes. In this review, we summarize what is currently known regarding the function, mechanism, and regulation of kidney clocks. Additionally, the effect of extrarenal physiological processes, such as endocrine and neuronal signals, on kidney function is also reviewed. Circadian rhythms in renal function are an integral part of kidney physiology, underscoring the importance of considering time of day as a key biological variable. The field of circadian renal physiology is of tremendous relevance, but with limited physiological and mechanistic information on the kidney clocks this is an area in need of extensive investigation.
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Affiliation(s)
- Hannah M Costello
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida
| | - Jermaine G Johnston
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida
- North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida
| | - Alexandria Juffre
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida
| | - G Ryan Crislip
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida
| | - Michelle L Gumz
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida
- North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida
- Center for Integrative Cardiovascular and Metabolic Diseases, University of Florida, Gainesville, Florida
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4
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Whittle RS, Keller N, Hall EA, Vellore HS, Stapleton LM, Findlay KH, Dunbar BJ, Diaz‐Artiles A. Gravitational Dose‐Response Curves for Acute Cardiovascular Hemodynamics and Autonomic Responses in a Tilt Paradigm. J Am Heart Assoc 2022; 11:e024175. [PMID: 35861832 PMCID: PMC9707822 DOI: 10.1161/jaha.121.024175] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background
The cardiovascular system is strongly dependent on the gravitational environment. Gravitational changes cause mechanical fluid shifts and, in turn, autonomic effectors influence systemic circulation and cardiac control. We implemented a tilt paradigm to (1) investigate the acute hemodynamic response across a range of directions of the gravitational vector, and (2) to generate specific dose‐response relationships of this gravitational dependency.
Methods and Results
Twelve male subjects were tilted from 45° head‐up tilt to 45° head‐down tilt in 15° increments, in both supine and prone postures. We measured the steady‐state hemodynamic response in a range of variables including heart rate, stroke volume, cardiac output, oxygen consumption, total peripheral resistance, blood pressure, and autonomic indices derived from heart rate variability analysis. There is a strong gravitational dependence in almost all variables considered, with the exception of oxygen consumption, whereas systolic blood pressure remained controlled to within ≈3% across the tilt range. Hemodynamic responses are primarily driven by differential loading on the baroreflex receptors, combined with differences in venous return to the heart. Thorax compression in the prone position leads to reduced venous return and increased sympathetic nervous activity, raising heart rate, and systemic vascular resistance while lowering cardiac output and stroke volume.
Conclusions
Gravitational dose‐response curves generated from these data provide a comprehensive baseline from which to assess the efficacy of potential spaceflight countermeasures. Results also assist clinical management of terrestrial surgery in prone posture or head‐down tilt positions.
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Affiliation(s)
- Richard S. Whittle
- Department of Aerospace Engineering Texas A&M University College Station TX
| | - Nathan Keller
- Department of Health and Kinesiology Texas A&M University College Station TX
| | - Eric A. Hall
- Department of Biomedical Engineering Texas A&M University College Station TX
| | | | | | | | - Bonnie J. Dunbar
- Department of Aerospace Engineering Texas A&M University College Station TX
| | - Ana Diaz‐Artiles
- Department of Aerospace Engineering Texas A&M University College Station TX
- Department of Health and Kinesiology Texas A&M University College Station TX
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5
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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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6
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Finger A, Kramer A. Mammalian circadian systems: Organization and modern life challenges. Acta Physiol (Oxf) 2021; 231:e13548. [PMID: 32846050 DOI: 10.1111/apha.13548] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/04/2020] [Accepted: 08/11/2020] [Indexed: 12/11/2022]
Abstract
Humans and other mammalian species possess an endogenous circadian clock system that has evolved in adaptation to periodically reoccurring environmental changes and drives rhythmic biological functions, as well as behavioural outputs with an approximately 24-hour period. In mammals, body clocks are hierarchically organized, encompassing a so-called pacemaker clock in the hypothalamic suprachiasmatic nucleus (SCN), non-SCN brain and peripheral clocks, as well as cell-autonomous oscillators within virtually every cell type. A functional clock machinery on the molecular level, alignment among body clocks, as well as synchronization between endogenous circadian and exogenous environmental cycles has been shown to be crucial for our health and well-being. Yet, modern life constantly poses widespread challenges to our internal clocks, for example artificial lighting, shift work and trans-meridian travel, potentially leading to circadian disruption or misalignment and the emergence of associated diseases. For instance many of us experience a mismatch between sleep timing on work and free days (social jetlag) in our everyday lives without being aware of health consequences that may arise from such chronic circadian misalignment, Hence, this review provides an overview of the organization and molecular built-up of the mammalian circadian system, its interactions with the outside world, as well as pathologies arising from circadian disruption and misalignment.
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Affiliation(s)
- Anna‐Marie Finger
- Laboratory of Chronobiology Institute for Medical immunology Charité Universitätsmedizin Berlin Berlin Germany
- Berlin Institute of Health (BIH) Berlin Germany
| | - Achim Kramer
- Laboratory of Chronobiology Institute for Medical immunology Charité Universitätsmedizin Berlin Berlin Germany
- Berlin Institute of Health (BIH) Berlin Germany
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7
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Approaching Gravity as a Continuum Using the Rat Partial Weight-Bearing Model. Life (Basel) 2020; 10:life10100235. [PMID: 33049988 PMCID: PMC7599661 DOI: 10.3390/life10100235] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/30/2020] [Accepted: 10/03/2020] [Indexed: 12/12/2022] Open
Abstract
For decades, scientists have relied on animals to understand the risks and consequences of space travel. Animals remain key to study the physiological alterations during spaceflight and provide crucial information about microgravity-induced changes. While spaceflights may appear common, they remain costly and, coupled with limited cargo areas, do not allow for large sample sizes onboard. In 1979, a model of hindlimb unloading (HU) was successfully created to mimic microgravity and has been used extensively since its creation. Four decades later, the first model of mouse partial weight-bearing (PWB) was developed, aiming at mimicking partial gravity environments. Return to the Lunar surface for astronauts is now imminent and prompted the need for an animal model closer to human physiology; hence in 2018, our laboratory created a new model of PWB for adult rats. In this review, we will focus on the rat model of PWB, from its conception to the current state of knowledge. Additionally, we will address how this new model, used in conjunction with HU, will help implement new paradigms allowing scientists to anticipate the physiological alterations and needs of astronauts. Finally, we will discuss the outstanding questions and future perspectives in space research and propose potential solutions using the rat PWB model.
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8
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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: 59] [Impact Index Per Article: 14.8] [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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9
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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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10
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Zhang X, Chu X, Chen L, Fu J, Wang S, Song J, Kan G, Jiang W, He G, Chen X, Li W. Simulated weightlessness procedure, head-down bed rest impairs adult neurogenesis in the hippocampus of rhesus macaque. Mol Brain 2019; 12:46. [PMID: 31072406 PMCID: PMC6509794 DOI: 10.1186/s13041-019-0459-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/16/2019] [Indexed: 11/10/2022] Open
Abstract
The microgravity environment in space can impact astronauts' cognitive and behavioral activities. However, due to the limitations of research conditions, studies of biological changes in the primate brain, such as neurogenesis, have been comparatively few. We take advantage of - 6° head-down bed rest (HDBR), one of the most implemented space analogue on the ground, to investigate the effects of weightlessness on neurogenesis of non-human primate brain. Rhesus Macaque monkeys were subjected to HDBR for 42 days to simulate weightlessness. BrdU (5-bromodeoxyuridin) and IdU (iododeoxyuridine) were intraperitoneally injected separately before or after HDBR to label the survival and proliferation of newborn neurons. Immunohistochemistry was performed to study the effect of simulated weightlessness on neurogenesis. BrdU staining showed that survival of newborn neurons was reduced, while there were fewer BrdU-positive neurons in the HDBR group compared with the control. Furthermore, IdU-positive neurons also decreased in the HDBR group suggesting a reduced proliferation capacity for these newborn neurons. Our results demonstrate the definite neurogenesis in the adult rhesus macaque hippocampus, and simulated weightlessness HDBR procedure impairs the adult neurogenesis.
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Affiliation(s)
- Xu Zhang
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Xixia Chu
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Lei Chen
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Juan Fu
- Department of Obstetrics and Gynecology, the First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Shuai Wang
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jinjing Song
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Guanghan Kan
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing, 100094, China
| | - Weizhong Jiang
- Department of Neurosurgery, Minhang Hospital, Fudan University, Shanghai, China
| | - Guang He
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Xiaoping Chen
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing, 100094, China.
| | - Weidong Li
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Institute of Psychology and Behavioral Sciences, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
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11
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Andreev-Andrievskiy AA, Popova AS, Lagereva EA, Vinogradova OL. Fluid shift versus body size: changes of hematological parameters and body fluid volume in hindlimb-unloaded mice, rats and rabbits. ACTA ACUST UNITED AC 2018; 221:jeb.182832. [PMID: 29950449 DOI: 10.1242/jeb.182832] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 06/11/2018] [Indexed: 01/12/2023]
Abstract
The cardiovascular system is adapted to gravity, and reactions to the loss of gravity in space are presumably dependent on body size. The dependence of hematological parameters and body fluid volume on simulated microgravity have never been studied as an allometric function before. Thus, we estimated red blood cell (RBC), blood and extracellular fluid volume in hindlimb-unloaded (HLU) or control (attached) mice, rats and rabbits. RBC decrease was found to be size independent, and the allometric dependency for RBC loss in HLU and control animals shared a common power (-0.054±0.008) but a different Y0 coefficient (8.66±0.40 and 10.73±0.49, respectively, P<0.05). Blood volume in HLU animals was unchanged compared with that of controls, disregarding body size. The allometric dependency of interstitial fluid volume in HLU and control mice shared Y0 (1.02±0.09) but had different powers N (0.708±0.017 and 0.648±0.016, respectively, P<0.05), indicating that the interstitial fluid volume increase during hindlimb unloading is more pronounced in larger animals. Our data underscore the importance of size-independent mechanisms of cardiovascular adaptation to weightlessness. Despite the fact that the use of mice hampers application of a straightforward translational approach, this species is useful for gravitational biology as a tool to investigate size-independent mechanisms of mammalian adaptation to microgravity.
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Affiliation(s)
- Alexander A Andreev-Andrievskiy
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, Russia .,M.V. Lomonosov Moscow State University, Biology Faculty, Moscow 119991, Russia
| | - Anfisa S Popova
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, Russia.,M.V. Lomonosov Moscow State University, Biology Faculty, Moscow 119991, Russia
| | - Evgeniia A Lagereva
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, Russia
| | - Olga L Vinogradova
- Institute of Biomedical Problems, Russian Academy of Sciences, Moscow 123007, Russia
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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: 119] [Impact Index Per Article: 14.9] [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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Li K, Guo X, Jin Z, Ouyang X, Zeng Y, Feng J, Wang Y, Yao L, Ma L. Effect of Simulated Microgravity on Human Brain Gray Matter and White Matter--Evidence from MRI. PLoS One 2015; 10:e0135835. [PMID: 26270525 PMCID: PMC4535759 DOI: 10.1371/journal.pone.0135835] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/27/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND There is limited and inconclusive evidence that space environment, especially microgravity condition, may affect microstructure of human brain. This experiment hypothesized that there would be modifications in gray matter (GM) and white matter (WM) of the brain due to microgravity. METHOD Eighteen male volunteers were recruited and fourteen volunteers underwent -6° head-down bed rest (HDBR) for 30 days simulated microgravity. High-resolution brain anatomical imaging data and diffusion tensor imaging images were collected on a 3T MR system before and after HDBR. We applied voxel-based morphometry and tract-based spatial statistics analysis to investigate the structural changes in GM and WM of brain. RESULTS We observed significant decreases of GM volume in the bilateral frontal lobes, temporal poles, parahippocampal gyrus, insula and right hippocampus, and increases of GM volume in the vermis, bilateral paracentral lobule, right precuneus gyrus, left precentral gyrus and left postcentral gyrus after HDBR. Fractional anisotropy (FA) changes were also observed in multiple WM tracts. CONCLUSION These regions showing GM changes are closely associated with the functional domains of performance, locomotion, learning, memory and coordination. Regional WM alterations may be related to brain function decline and adaption. Our findings provide the neuroanatomical evidence of brain dysfunction or plasticity in microgravity condition and a deeper insight into the cerebral mechanisms in microgravity condition.
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Affiliation(s)
- Ke Li
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
- Magnetic Resonance Center, 306 Hospital of PLA, Beijing, China
| | - Xiaojuan Guo
- College of Information Science and Technology, Beijing Normal University, Beijing, China
| | - Zhen Jin
- Magnetic Resonance Center, 306 Hospital of PLA, Beijing, China
| | - Xin Ouyang
- College of Information Science and Technology, Beijing Normal University, Beijing, China
| | - Yawei Zeng
- Magnetic Resonance Center, 306 Hospital of PLA, Beijing, China
| | - Jinsheng Feng
- The Third Laboratory, China Astronaut Research and Training Centre, Beijing, China
| | - Yu Wang
- Outpatient Department of 61599 Unit of PLA, Beijing, China
| | - Li Yao
- College of Information Science and Technology, Beijing Normal University, Beijing, China
| | - Lin Ma
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
- * E-mail:
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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: 27] [Impact Index Per Article: 3.0] [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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Ma L, Ma J, Xu K. Effect of spaceflight on the circadian rhythm, lifespan and gene expression of Drosophila melanogaster. PLoS One 2015; 10:e0121600. [PMID: 25798821 PMCID: PMC4370389 DOI: 10.1371/journal.pone.0121600] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 02/16/2015] [Indexed: 12/20/2022] Open
Abstract
Space travelers are reported to experience circadian rhythm disruption during spaceflight. However, how the space environment affects circadian rhythm is yet to be determined. The major focus of this study was to investigate the effect of spaceflight on the Drosophila circadian clock at both the behavioral and molecular level. We used China's Shenzhou-9 spaceship to carry Drosophila. After 13 days of spaceflight, behavior tests showed that the flies maintained normal locomotor activity rhythm and sleep pattern. The expression level and rhythm of major clock genes were also unaffected. However, expression profiling showed differentially regulated output genes of the circadian clock system between space flown and control flies, suggesting that spaceflight affected the circadian output pathway. We also investigated other physiological effects of spaceflight such as lipid metabolism and lifespan, and searched genes significantly affected by spaceflight using microarray analysis. These results provide new information on the effects of spaceflight on circadian rhythm, lipid metabolism and lifespan. Furthermore, we showed that studying the effect of spaceflight on gene expression using samples collected at different Zeitgeber time could obtain different results, suggesting the importance of appropriate sampling procedures in studies on the effects of spaceflight.
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Affiliation(s)
- Lingling Ma
- Laboratory of Space Microbiology, Shenzhou Space Biotechnology Group, China Academy of Space Technology, Beijing, China
| | - Jun Ma
- Laboratory of Space Microbiology, Shenzhou Space Biotechnology Group, China Academy of Space Technology, Beijing, China
| | - Kanyan Xu
- Laboratory of Space Microbiology, Shenzhou Space Biotechnology Group, China Academy of Space Technology, Beijing, China
- * E-mail:
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Liu Z, Wan Y, Zhang L, Tian Y, Lv K, Li Y, Wang C, Chen X, Chen S, Guo J. Alterations in the heart rate and activity rhythms of three orbital astronauts on a space mission. LIFE SCIENCES IN SPACE RESEARCH 2015; 4:62-66. [PMID: 26177621 DOI: 10.1016/j.lssr.2015.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 12/05/2014] [Accepted: 01/03/2015] [Indexed: 06/04/2023]
Abstract
Environmental factors in space are dramatically different from those on Earth. The spaceflight environment has been known to influence human physiology and behavior on orbital missions. In this study, we investigated alterations in the diurnal rhythms of activity and heart rate of three Chinese astronauts on a space mission. An analysis of the heart rate data showed a significant decrease in heart rate amplitudes during flight in all three subjects. The heart rate amplitudes of all the three astronauts were significantly dampened during flight, and the minimum as well as the maximum value of heart rate increased after flight. A phase shift in heart rate was observed in one of the three astronauts after flight. These results demonstrate the influence of spaceflight on heart physiology and function. In addition, a significant decrease in body trunk activity and rhythmicity occurred during flight, demonstrating that the spaceflight environment disturbs motion adaptation and diurnal activity rhythms.
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Affiliation(s)
- Zhizhen Liu
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, P.O. Box 5132-26, Beijing, China
| | - Yufeng Wan
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Lin Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yu Tian
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, P.O. Box 5132-26, Beijing, China
| | - Ke Lv
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing 100094, China
| | - Yinghui Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Centre, Beijing 100094, China
| | - Chunhui Wang
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, P.O. Box 5132-26, Beijing, China
| | - Xiaoping Chen
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, P.O. Box 5132-26, Beijing, China
| | - Shanguang Chen
- National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, P.O. Box 5132-26, Beijing, China
| | - Jinhu Guo
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
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Keith Sharp M, Batzel JJ, Montani JP. Space physiology IV: mathematical modeling of the cardiovascular system in space exploration. Eur J Appl Physiol 2013; 113:1919-37. [PMID: 23539439 DOI: 10.1007/s00421-013-2623-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2012] [Accepted: 03/03/2013] [Indexed: 01/03/2023]
Abstract
Mathematical modeling represents an important tool for analyzing cardiovascular function during spaceflight. This review describes how modeling of the cardiovascular system can contribute to space life science research and illustrates this process via modeling efforts to study postflight orthostatic intolerance (POI), a key issue for spaceflight. Examining this application also provides a context for considering broader applications of modeling techniques to the challenges of bioastronautics. POI, which affects a large fraction of astronauts in stand tests upon return to Earth, presents as dizziness, fainting and other symptoms, which can diminish crew performance and cause safety hazards. POI on the Moon or Mars could be more critical. In the field of bioastronautics, POI has been the dominant application of cardiovascular modeling for more than a decade, and a number of mechanisms for POI have been investigated. Modeling approaches include computational models with a range of incorporated factors and hemodynamic sophistication, and also physical models tested in parabolic and orbital flight. Mathematical methods such as parameter sensitivity analysis can help identify key system mechanisms. In the case of POI, this could lead to more effective countermeasures. Validation is a persistent issue in modeling efforts, and key considerations and needs for experimental data to synergistically improve understanding of cardiovascular responses are outlined. Future directions in cardiovascular modeling include subject-specific assessment of system status, as well as research on integrated physiological responses, leading, for instance, to assessment of subject-specific susceptibility to POI or effects of cardiovascular alterations on muscular, vision and cognitive function.
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Affiliation(s)
- M Keith Sharp
- Biofluid Mechanics Laboratory, Department of Mechanical Engineering, University of Louisville, Louisville, KY, USA
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Liao Y, Zhang J, Huang Z, Xi Y, Zhang Q, Zhu T, Liu X. Altered baseline brain activity with 72 h of simulated microgravity--initial evidence from resting-state fMRI. PLoS One 2012; 7:e52558. [PMID: 23285086 PMCID: PMC3528642 DOI: 10.1371/journal.pone.0052558] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 11/15/2012] [Indexed: 11/19/2022] Open
Abstract
To provide the basis and reference to further insights into the neural activity of the human brain in a microgravity environment, we discuss the amplitude changes of low-frequency brain activity fluctuations using a simulated microgravity model. Twelve male participants between 24 and 31 years old received resting-state fMRI scans in both a normal condition and after 72 hours in a -6° head down tilt (HDT). A paired sample t-test was used to test the amplitude differences of low-frequency brain activity fluctuations between these two conditions. With 72 hours in a -6° HDT, the participants showed a decreased amplitude of low-frequency fluctuations in the left thalamus compared with the normal condition (a combined threshold of P<0.005 and a minimum cluster size of 351 mm(3) (13 voxels), which corresponded with the corrected threshold of P<0.05 determined by AlphaSim). Our findings indicate that a gravity change-induced redistribution of body fluid may disrupt the function of the left thalamus in the resting state, which may contribute to reduced motor control abilities and multiple executive functions in astronauts in a microgravity environment.
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Affiliation(s)
- Yang Liao
- Department of Psychology, School of Aerospace Medicine, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Jinsong Zhang
- Department of Radiology, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Zhiping Huang
- Department of Psychology, School of Aerospace Medicine, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Yibin Xi
- Department of Radiology, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Qianru Zhang
- Department of Psychology, School of Aerospace Medicine, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Tianli Zhu
- Department of Psychology, School of Aerospace Medicine, Fourth Military Medical University, Xi’an, Shaanxi, China
| | - Xufeng Liu
- Department of Psychology, School of Aerospace Medicine, Fourth Military Medical University, Xi’an, Shaanxi, China
- * E-mail:
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Abstract
PURPOSE OF REVIEW Circadian variation is commonly seen in healthy people; aberration in these biological rhythms is an early sign of disease. Impaired circadian variation of blood pressure (BP) has been shown to be associated with greater target organ damage and with an elevated risk of cardiovascular events independent of the BP load. The purpose of this review is to examine the physiology of circadian BP variation and propose a tripartite model that explains the regulation of circadian BP. RECENT FINDINGS The time-keeper in mammals resides centrally in the suprachiasmatic nucleus. Apart from this central clock, molecular clocks exist in most peripheral tissues including vascular tissue and the kidney. These molecular clocks regulate sodium balance, sympathetic function and vascular tone. A physiological model is proposed that integrates our understanding of molecular clocks in mice with the circadian BP variation among humans. The master regulator in this proposed model is the sleep-activity cycle. The equivalents of peripheral clocks are endothelial and adrenergic functions. Thus, in the proposed model, the variation in circadian BP is dependent upon three major factors: physical activity, autonomic function, and sodium sensitivity. SUMMARY The integrated consideration of physical activity, autonomic function, and sodium sensitivity appears to explain the physiology of circadian BP variation and the pathophysiology of disrupted BP rhythms in various conditions and disease states. Our understanding of molecular clocks in mice may help to explain the provenance of blunted circadian BP variation even among astronauts.
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Cardiovascular research in space. Respir Physiol Neurobiol 2009; 169 Suppl 1:S2-3. [DOI: 10.1016/j.resp.2009.07.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 11/21/2022]
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