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Tahimic CGT, Steczina S, Sebastian A, Hum NR, Abegaz M, Terada M, Cimini M, Goukassian DA, Schreurs AS, Hoban-Higgins TM, Fuller CA, Loots GG, Globus RK, Shirazi-Fard Y. Simulated Microgravity Alters Gene Regulation Linked to Immunity and Cardiovascular Disease. Genes (Basel) 2024; 15:975. [PMID: 39202335 PMCID: PMC11353732 DOI: 10.3390/genes15080975] [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: 06/29/2024] [Revised: 07/18/2024] [Accepted: 07/19/2024] [Indexed: 09/03/2024] Open
Abstract
Microgravity exposure induces a cephalad fluid shift and an overall reduction in physical activity levels which can lead to cardiovascular deconditioning in the absence of countermeasures. Future spaceflight missions will expose crew to extended periods of microgravity among other stressors, the effects of which on cardiovascular health are not fully known. In this study, we determined cardiac responses to extended microgravity exposure using the rat hindlimb unloading (HU) model. We hypothesized that exposure to prolonged simulated microgravity and subsequent recovery would lead to increased oxidative damage and altered expression of genes involved in the oxidative response. To test this hypothesis, we examined hearts of male (three and nine months of age) and female (3 months of age) Long-Evans rats that underwent HU for various durations up to 90 days and reambulated up to 90 days post-HU. Results indicate sex-dependent changes in oxidative damage marker 8-hydroxydeoxyguanosine (8-OHdG) and antioxidant gene expression in left ventricular tissue. Three-month-old females displayed elevated 8-OHdG levels after 14 days of HU while age-matched males did not. In nine-month-old males, there were no differences in 8-OHdG levels between HU and normally loaded control males at any of the timepoints tested following HU. RNAseq analysis of left ventricular tissue from nine-month-old males after 14 days of HU revealed upregulation of pathways involved in pro-inflammatory signaling, immune cell activation and differential expression of genes associated with cardiovascular disease progression. Taken together, these findings provide a rationale for targeting antioxidant and immune pathways and that sex differences should be taken into account in the development of countermeasures to maintain cardiovascular health in space.
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Affiliation(s)
- Candice G. T. Tahimic
- Department of Biology, University of North Florida, Jacksonville, FL 32224, USA
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
| | - Sonette Steczina
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
- Blue Marble Space Institute of Science, Seattle, WA 98104, USA
| | - Aimy Sebastian
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (G.G.L.)
| | - Nicholas R. Hum
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (G.G.L.)
| | - Metadel Abegaz
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
- Blue Marble Space Institute of Science, Seattle, WA 98104, USA
| | - Masahiro Terada
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
- Universities Space Research Association, Washington, DC 20024, USA
| | - Maria Cimini
- Temple University School of Medicine, Philadelphia, PA 19140, USA;
| | - David A. Goukassian
- Cardiovascular Research Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA;
| | - Ann-Sofie Schreurs
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
- Universities Space Research Association, Washington, DC 20024, USA
| | - Tana M. Hoban-Higgins
- Department of Neurobiology, Physiology and Behavior, University of California Davis, Davis, CA 95616, USA
| | - Charles A. Fuller
- Department of Neurobiology, Physiology and Behavior, University of California Davis, Davis, CA 95616, USA
| | - Gabriela G. Loots
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA (G.G.L.)
- Department of Orthopedic Surgery, University of California Davis Health, Sacramento, CA 95817, USA
| | - Ruth K. Globus
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
| | - Yasaman Shirazi-Fard
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA 94035, USA (M.A.); (Y.S.)
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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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3
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The impact of a short-period head-down tilt on executive function in younger adults. Sci Rep 2022; 12:20888. [PMID: 36463320 PMCID: PMC9719537 DOI: 10.1038/s41598-022-25123-3] [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: 12/03/2021] [Accepted: 11/24/2022] [Indexed: 12/07/2022] Open
Abstract
Microgravity has been shown to be a significant stressor on the cardiovascular system and the brain due to the redistribution of fluids that occurs in the absence of gravitational force, but there is scarce literature surrounding the effects of microgravity on cerebral hemodynamics and cognition. Understanding the early effects that simulated gravity has on cognitive function is essential for developing proper physical and cognitive countermeasures to assure safe and effective cognitive/decisions making while astronauts prepare for the initial launch or when they arrive in a microgravity environment. Therefore, this study aims to determine how an acute simulation of microgravity would alter cerebral oxygenation and executive functions. Sixty-five young healthy participants (22 ± 6 years, 21 females) completed a thirty (30) minute horizontal (00 tilt) followed by a 90-min - 6° head-down-tilt (HDT) protocol. Cerebral oxygenation in the prefrontal cortex was monitored throughout the testing session using near-infrared spectroscopy. Cognition was also measured using a computerized Stroop Task. Our results demonstrate that cerebral oxygenation was higher during HDT compared to the horizontal supine position (9.11 ± 1.3 vs. 7.51 ± 1.8, p = 0.02). For the cognitive results, the non-executive performance of the Stroop task remained stable during HDT (652.46 ± 19.3 vs. 632.49 ± 14.5, p = 0.09). However, reaction time during the executive task performance was improved after the HDT (1058 ± 195-950 ± 158 ms, p < 0.01). Our results suggest that an acute bout of simulated microgravity can enhance executive functioning.
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Abstract
The pathogenesis of irritable bowel syndrome (IBS)-a disorder of gut-brain interaction that affects up to 10% of the world's population-remains uncertain. It is puzzling that a disorder so prevalent and archetypal among humans can be explained by disparate theories, respond to treatments with vastly different mechanisms of action, and present with a dazzling array of comorbidities. It is reasonable to question whether there is a unifying factor that binds these divergent theories and observations, and if so, what that factor might be. This article offers a testable hypothesis that seeks to accommodate the manifold theories, clinical symptoms, somatic comorbidities, neuropsychological features, and treatment outcomes of IBS by describing the syndrome in relation to a principal force of human evolution: gravity. In short, the hypothesis proposed here is that IBS may result from ineffective anatomical, physiological, and neuropsychological gravity management systems designed to optimize gastrointestinal form and function, protect somatic and visceral integrity, and maximize survival in a gravity-bound world. To explain this unconventional hypothesis of IBS pathogenesis, referred to herein as the gravity hypothesis, this article reviews the influence of gravity on human evolution; discusses how Homo sapiens imperfectly evolved to manage this universal force of attraction; and explores the mechanical, microbial, and neuropsychological consequences of gravity intolerance with a focus on explaining IBS. This article concludes by considering the diagnostic and therapeutic implications of this new hypothesis and proposes experiments to support or reject this line of inquiry. It is hoped that the ideas in this thought experiment may also help encourage new or different ways of thinking about this common disorder.
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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: 32] [Impact Index Per Article: 10.7] [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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6
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Matić Z, Platiša MM, Kalauzi A, Bojić T. Slow 0.1 Hz Breathing and Body Posture Induced Perturbations of RRI and Respiratory Signal Complexity and Cardiorespiratory Coupling. Front Physiol 2020; 11:24. [PMID: 32132926 PMCID: PMC7040454 DOI: 10.3389/fphys.2020.00024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 01/14/2020] [Indexed: 12/21/2022] Open
Abstract
Objective: We explored the physiological background of the non-linear operating mode of cardiorespiratory oscillators as the fundamental question of cardiorespiratory homeodynamics and as a prerequisite for the understanding of neurocardiovascular diseases. We investigated 20 healthy human subjects for changes using electrocardiac RR interval (RRI) and respiratory signal (Resp) Detrended Fluctuation Analysis (DFA, α1RRI, α2RRI, α1Resp, α2Resp), Multiple Scaling Entropy (MSERRI1-4, MSERRI5-10, MSEResp1-4, MSEResp5-10), spectral coherence (CohRRI-Resp), cross DFA (ρ1 and ρ2) and cross MSE (XMSE1-4 and XMSE5-10) indices in four physiological conditions: supine with spontaneous breathing, standing with spontaneous breathing, supine with 0.1 Hz breathing and standing with 0.1 Hz breathing. Main results: Standing is primarily characterized by the change of RRI parameters, insensitivity to change with respiratory parameters, decrease of CohRRI-Resp and insensitivity to change of in ρ1, ρ2, XMSE1-4, and XMSE5-10. Slow breathing in supine position was characterized by the change of the linear and non-linear parameters of both signals, reflecting the dominant vagal RRI modulation and the impact of slow 0.1 Hz breathing on Resp parameters. CohRRI-Resp did not change with respect to supine position, while ρ1 increased. Slow breathing in standing reflected the qualitatively specific state of autonomic regulation with striking impact on both cardiac and respiratory parameters, with specific patterns of cardiorespiratory coupling. Significance: Our results show that cardiac and respiratory short term and long term complexity parameters have different, state dependent patterns. Sympathovagal non-linear interactions are dependent on the pattern of their activation, having different scaling properties when individually activated with respect to the state of their joint activation. All investigated states induced a change of α1 vs. α2 relationship, which can be accurately expressed by the proposed measure-inter-fractal angle θ. Short scale (α1 vs. MSE1-4) and long scale (α2 vs. MSE5-10) complexity measures had reciprocal interrelation in standing with 0.1 Hz breathing, with specific cardiorespiratory coupling pattern (ρ1 vs. XMSE1-4). These results support the hypothesis of hierarchical organization of cardiorespiratory complexity mechanisms and their recruitment in ascendant manner with respect to the increase of behavioral challenge complexity. Specific and comprehensive cardiorespiratory regulation in standing with 0.1 Hz breathing suggests this state as the potentially most beneficial maneuver for cardiorespiratory conditioning.
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Affiliation(s)
- Zoran Matić
- Biomedical Engineering and Technology, University of Belgrade, Belgrade, Serbia
| | - Mirjana M. Platiša
- Faculty of Medicine, Institute of Biophysics, University of Belgrade, Belgrade, Serbia
| | - Aleksandar Kalauzi
- Department for Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia
| | - Tijana Bojić
- Laboratory for Radiobiology and Molecular Genetics-080, Institute for Nuclear Sciences Vinča, University of Belgrade, Belgrade, Serbia
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7
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Tahimic CGT, Paul AM, Schreurs AS, Torres SM, Rubinstein L, Steczina S, Lowe M, Bhattacharya S, Alwood JS, Ronca AE, Globus RK. Influence of Social Isolation During Prolonged Simulated Weightlessness by Hindlimb Unloading. Front Physiol 2019; 10:1147. [PMID: 31572207 PMCID: PMC6753329 DOI: 10.3389/fphys.2019.01147] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 08/22/2019] [Indexed: 12/15/2022] Open
Abstract
The hindlimb unloading (HU) model has been used extensively to simulate the cephalad fluid shift and musculoskeletal disuse observed in spaceflight with its application expanding to study immune, cardiovascular and central nervous system responses, among others. Most HU studies are performed with singly housed animals, although social isolation also can substantially impact behavior and physiology, and therefore may confound HU experimental results. Other HU variants that allow for paired housing have been developed although no systematic assessment has been made to understand the effects of social isolation on HU outcomes. Hence, we aimed to determine the contribution of social isolation to tissue responses to HU. To accomplish this, we developed a refinement to the traditional NASA Ames single housing HU system to accommodate social housing in pairs, retaining desirable features of the original design. We conducted a 30-day HU experiment with adult, female mice that were either singly or socially housed. HU animals in both single and social housing displayed expected musculoskeletal deficits versus housing matched, normally loaded (NL) controls. However, select immune and hypothalamic-pituitary-adrenal (HPA) axis responses were differentially impacted by the HU social environment relative to matched NL controls. HU led to a reduction in % CD4+ T cells in singly housed, but not in socially housed mice. Unexpectedly, HU increased adrenal gland mass in socially housed but not singly housed mice, while social isolation increased adrenal gland mass in NL controls. HU also led to elevated plasma corticosterone levels at day 30 in both singly and socially housed mice. Thus, musculoskeletal responses to simulated weightlessness are similar regardless of social environment with a few differences in adrenal and immune responses. Our findings show that combined stressors can mask, not only exacerbate, select responses to HU. These findings further expand the utility of the HU model for studying possible combined effects of spaceflight stressors.
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Affiliation(s)
- Candice G T Tahimic
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,KBR, Houston, TX, United States
| | - Amber M Paul
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Universities Space Research Association, Columbia, MD, United States
| | - Ann-Sofie Schreurs
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,KBR, Houston, TX, United States
| | - Samantha M Torres
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Blue Marble Space Institute of Science, Seattle, WA, United States
| | - Linda Rubinstein
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Universities Space Research Association, Columbia, MD, United States
| | - Sonette Steczina
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Blue Marble Space Institute of Science, Seattle, WA, United States
| | - Moniece Lowe
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Blue Marble Space Institute of Science, Seattle, WA, United States
| | - Sharmila Bhattacharya
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States
| | - Joshua S Alwood
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States
| | - April E Ronca
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States.,Department of Obstetrics and Gynecology, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Ruth K Globus
- Space Biosciences Division, NASA Ames Research Center, Moffett Field, CA, United States
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8
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Prisk GK. Pulmonary challenges of prolonged journeys to space: taking your lungs to the moon. Med J Aust 2019; 211:271-276. [PMID: 31420881 DOI: 10.5694/mja2.50312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Space flight presents a set of physiological challenges to the space explorer which result from the absence of gravity (or in the case of planetary exploration, partial gravity), radiation exposure, isolation and a prolonged period in a confined environment, distance from Earth, the need to venture outside in the hostile environment of the destination, and numerous other factors. Gravity affects regional lung function, and the human lung shows considerable alteration in function in low gravity; however, this alteration does not result in deleterious changes that compromise lung function upon return to Earth. The decompression stress associated with extravehicular activity, or spacewalk, does not appear to compromise lung function, and future habitat (living quarter) designs can be engineered to minimise this stress. Dust exposure is a significant health hazard in occupational settings such as mining, and exposure to extraterrestrial dust is an almost inevitable consequence of planetary exploration. The combination of altered pulmonary deposition of extraterrestrial dust and the potential for the dust to be highly toxic likely makes dust exposure the greatest threat to the lung in planetary exploration.
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Affiliation(s)
- G Kim Prisk
- University of California, San Diego, La Jolla, CA, USA
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9
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Prisk GK. Effects of Partial Gravity on the Function and Particle Handling of the Human Lung. CURRENT PATHOBIOLOGY REPORTS 2019; 6:159-166. [PMID: 30687585 DOI: 10.1007/s40139-018-0174-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Purpose of Review The challenges presented to the lung by the space environment are the effects of prolonged absence of gravity, the challenges of decompression stress associated with spacewalking, and the changes in the deposition of inhaled particulate matter. Recent Findings Although there are substantial changes in the function of the lung in partial gravity, the lung is largely unaffected by sustained exposure, returning rapidly to a normal state after return to 1G. Provided there is adequate denitrogenation prior to a spacewalk, avoiding the development of venous gas emboli, the lung copes well with the low pressure environment of the spacesuit. Particulate deposition is reduced in partial gravity, but where that deposition occurs is likely in the more peripheral airspaces, with associated longer retention times, potentially raising the toxicological potential of toxic dusts. Summary Despite its delicate structure the lung performs well in partial gravity, with the greatest threat likely arising from inhaled particulate matter (extra-terrestrial dusts).
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Affiliation(s)
- G Kim Prisk
- Department of Medicine, University of California, San Diego
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10
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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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Hallgren E, Migeotte PF, Kornilova L, Delière Q, Fransen E, Glukhikh D, Moore ST, Clément G, Diedrich A, MacDougall H, Wuyts FL. Dysfunctional vestibular system causes a blood pressure drop in astronauts returning from space. Sci Rep 2015; 5:17627. [PMID: 26671177 PMCID: PMC4680856 DOI: 10.1038/srep17627] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/03/2015] [Indexed: 02/08/2023] Open
Abstract
It is a challenge for the human body to maintain stable blood pressure while standing. The body’s failure to do so can lead to dizziness or even fainting. For decades it has been postulated that the vestibular organ can prevent a drop in pressure during a position change – supposedly mediated by reflexes to the cardiovascular system. We show – for the first time – a significant correlation between decreased functionality of the vestibular otolith system and a decrease in the mean arterial pressure when a person stands up. Until now, no experiments on Earth could selectively suppress both otolith systems; astronauts returning from space are a unique group of subjects in this regard. Their otolith systems are being temporarily disturbed and at the same time they often suffer from blood pressure instability. In our study, we observed the functioning of both the otolith and the cardiovascular system of the astronauts before and after spaceflight. Our finding indicates that an intact otolith system plays an important role in preventing blood pressure instability during orthostatic challenges. Our finding not only has important implications for human space exploration; they may also improve the treatment of unstable blood pressure here on Earth.
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Affiliation(s)
- Emma Hallgren
- Antwerp University Research center for Equilibrium and Aerospace, Dept. of Biomedical Physics, University of Antwerp, Belgium
| | - Pierre-François Migeotte
- Université libre de Bruxelles &Erasmus Hospital, Department of Cardiology, Laboratory of Physics and Physiology, Brussels, Belgium
| | - Ludmila Kornilova
- Laboratory of Vestibular Physiology, Institute of Biomedical Problems of the Russian academy of sciences, Moscow, Russia
| | - Quentin Delière
- Université libre de Bruxelles &Erasmus Hospital, Department of Cardiology, Laboratory of Physics and Physiology, Brussels, Belgium
| | - Erik Fransen
- StatUa center for statistics, University of Antwerp, Antwerp, Belgium
| | - Dmitrii Glukhikh
- Laboratory of Vestibular Physiology, Institute of Biomedical Problems of the Russian academy of sciences, Moscow, Russia
| | - Steven T Moore
- Human Aerospace Laboratory, Icahn School of Medicine at Mount Sinai, New York City, USA
| | - Gilles Clément
- Lyon Neuroscience Research Center, IMPACT Team, University of Lyon, France
| | - André Diedrich
- Autonomic Dysfunction Center, Vanderbilt University School of Medicine, Nashville, USA
| | - Hamish MacDougall
- Sydney Human Factors Research, School of Psychology, University of Sydney, Australia
| | - Floris L Wuyts
- Antwerp University Research center for Equilibrium and Aerospace, Dept. of Biomedical Physics, University of Antwerp, Belgium
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12
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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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13
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Xu D, Shoemaker JK, Blaber AP, Arbeille P, Fraser K, Hughson RL. Reduced heart rate variability during sleep in long-duration spaceflight. Am J Physiol Regul Integr Comp Physiol 2013; 305:R164-70. [PMID: 23637139 DOI: 10.1152/ajpregu.00423.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Limited data are available to describe the regulation of heart rate (HR) during sleep in spaceflight. Sleep provides a stable supine baseline during preflight Earth recordings for comparison of heart rate variability (HRV) over a wide range of frequencies using both linear, complexity, and fractal indicators. The current study investigated the effect of long-duration spaceflight on HR and HRV during sleep in seven astronauts aboard the International Space Station up to 6 mo. Measurements included electrocardiographic waveforms from Holter monitors and simultaneous movement records from accelerometers before, during, and after the flights. HR was unchanged inflight and elevated postflight [59.6 ± 8.9 beats per minute (bpm) compared with preflight 53.3 ± 7.3 bpm; P < 0.01]. Compared with preflight data, HRV indicators from both time domain and power spectral analysis methods were diminished inflight from ultralow to high frequencies and partially recovered to preflight levels after landing. During inflight and at postflight, complexity and fractal properties of HR were not different from preflight properties. Slow fluctuations (<0.04 Hz) in HR presented moderate correlations with movements during sleep, partially accounting for the reduction in HRV. In summary, substantial reduction in HRV was observed with linear, but not with complexity and fractal, methods of analysis. These results suggest that periodic elements that influence regulation of HR through reflex mechanisms are altered during sleep in spaceflight but that underlying system complexity and fractal dynamics were not altered.
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Affiliation(s)
- D Xu
- Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
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14
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Bai Y, Tsunematsu T, Jiao Q, Ohnuki Y, Mototani Y, Shiozawa K, Jin M, Cai W, Jin HL, Fujita T, Ichikawa Y, Suita K, Kurotani R, Yokoyama U, Sato M, Iwatsubo K, Ishikawa Y, Okumura S. Pharmacological stimulation of type 5 adenylyl cyclase stabilizes heart rate under both microgravity and hypergravity induced by parabolic flight. J Pharmacol Sci 2012; 119:381-9. [PMID: 22850613 DOI: 10.1254/jphs.12102fp] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
We previously demonstrated that type 5 adenylyl cyclase (AC5) functions in autonomic regulation in the heart. Based on that work, we hypothesized that pharmacological modulation of AC5 activity could regulate the autonomic control of the heart rate under micro- and hypergravity. To test this hypothesis, we selected the approach of activating AC5 activity in mice with a selective AC5 activator (NKH477) or inhibitor (vidarabine) and examining heart rate variability during parabolic flight. The standard deviation of normal R-R intervals, a marker of total autonomic variability, was significantly greater under micro- and hypergravity in the vidarabine group, while there were no significant changes in the NKH477 group, suggesting that autonomic regulation was unstable in the vidarabine group. The ratio of low frequency and high frequency (HF) in heart rate variability analysis, a marker of sympathetic activity, became significantly decreased under micro- and hypergravity in the NKH477 group, while there was no such decrease in the vidarabine group. Normalized HF, a marker of parasympathetic activity, became significantly greater under micro- and hypergravity in the NKH477 group. In contrast, there was no such increase in the vidarabine group. This study is the first to indicate that pharmacological modulation of AC5 activity under micro- and hypergravity could be useful to regulate the autonomic control of the heart rate.
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Affiliation(s)
- Yunzhe Bai
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Japan
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15
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Hughson RL, Shoemaker JK, Blaber AP, Arbeille P, Greaves DK, Pereira-Junior PP, Xu D. Cardiovascular regulation during long-duration spaceflights to the International Space Station. J Appl Physiol (1985) 2012; 112:719-27. [DOI: 10.1152/japplphysiol.01196.2011] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Early evidence from long-duration flights indicates general cardiovascular deconditioning, including reduced arterial baroreflex gain. The current study investigated the spontaneous baroreflex and markers of cardiovascular control in six male astronauts living for 2–6 mo on the International Space Station. Measurements were made from the finger arterial pressure waves during spontaneous breathing (SB) in the supine posture pre- and postflight and during SB and paced breathing (PB, 0.1 Hz) in a seated posture pre- and postflight, as well as early and late in the missions. There were no changes in preflight measurements of heart rate (HR), blood pressure (BP), or spontaneous baroreflex compared with in-flight measurements. There were, however, increases in the estimate of left ventricular ejection time index and a late in-flight increase in cardiac output (CO). The high-frequency component of RR interval spectral power, arterial pulse pressure, and stroke volume were reduced in-flight. Postflight there was a small increase compared with preflight in HR (60.0 ± 9.4 vs. 54.9 ± 9.6 beats/min in the seated posture, P < 0.05) and CO (5.6 ± 0.8 vs. 5.0 ± 1.0 l/min, P < 0.01). Arterial baroreflex response slope was not changed during spaceflight, while a 34% reduction from preflight in baroreflex slope during postflight PB was significant (7.1 ± 2.4 vs. 13.4 ± 6.8 ms/mmHg), but a smaller average reduction (25%) during SB (8.0 ± 2.1 vs. 13.6 ± 7.4 ms/mmHg) was not significant. Overall, these data show no change in markers of cardiovascular stability during long-duration spaceflight and only relatively small changes postflight at rest in the seated position. The current program routine of countermeasures on the International Space Station provided sufficient stimulus to maintain cardiovascular stability under resting conditions during long-duration spaceflight.
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Affiliation(s)
- R. L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
| | - J. K. Shoemaker
- School of Kinesiology and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario,
| | - A. P. Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
| | - P. Arbeille
- Unite Medecine Physiologie Spatiale, CERCOM, EFMP CHU Trousseau, Tours, France
| | - D. K. Greaves
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
| | | | - D. Xu
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
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16
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Migeotte PF, Pattyn N, Vanspauwen R, Neyt X, Acheroy M, Van de Heyning P, Wuyts FL. Respiratory sinus arrhythmia on the ESA-short-arm human centrifuge. ACTA ACUST UNITED AC 2010; 28:86-91. [PMID: 19914893 DOI: 10.1109/memb.2009.934618] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this article, we investigated the hypothesis that the effects of hypergravity on respiratory sinus arrhythmia (RSA) can mimic the effects observed after spaceflight cardiovascular deconditioning. Artificial gravity along the head-to-feet axis on a short-arm centrifuge induces gravity gradients. This physiological condition of significantly higher g at the feet than at the heart level is specific and likely induces blood sequestration in the lower limbs. After spaceflight, astronauts are in a condition of cardiovascular deconditioning, where blood pooling in the lower part of the body and autonomic adaptation are factors contributing to orthostatic intolerance and changes in heart-rate variability (HRV). ECG and respiration were recorded during imposed and controlled breathing (ICB) protocols, which were repeated at different levels of artificial gravity as well as during supine and standing control conditions, and the changes were analyzed.
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Affiliation(s)
- Pierre-François Migeotte
- Signal and Image Centre, Electrical Engineering Department, Royal Military Academy, 30 Avenue de la Renaissance, B-1000 Brussels, Belgium.
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17
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Verheyden B, Liu J, Beckers F, Aubert AE. Operational point of neural cardiovascular regulation in humans up to 6 months in space. J Appl Physiol (1985) 2010; 108:646-54. [DOI: 10.1152/japplphysiol.00883.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Entering weightlessness affects central circulation in humans by enhancing venous return and cardiac output. We tested whether the operational point of neural cardiovascular regulation in space sets accordingly to adopt a level close to that found in the ground-based horizontal position. Heart rate (HR), finger blood and brachial blood pressure (BP), and respiratory frequency were collected in 11 astronauts from nine space missions. Recordings were made in supine and standing positions at least 10 days before launch and during spaceflight ( days 5– 19, 45– 67, 77– 116, 146– 180). Cross-correlation analyses of HR and systolic BP were used to measure three complementary aspects of cardiac baroreflex modulation: 1) baroreflex sensitivity, 2) number of effective baroreflex estimates, and 3) baroreflex time delay. A fixed breathing protocol was performed to measure respiratory sinus arrhythmia and low-frequency power of systolic BP variability. We found that HR and mean arterial pressure did not differ from preflight supine values for up to 6 mo in space. Respiration frequency tended to decrease during prolonged spaceflight. Concerning neural markers of cardiovascular regulation, we observed in-flight adaptations toward homeostatic conditions similar to those found in the ground-based supine position. Surprisingly, this was not the case for baroreflex time delay distribution, which had somewhat longer latencies in space. Except for this finding, our results confirm that the operational point of neural cardiovascular regulation in space sets to a level close to that of an Earth-based supine position. This adaptation level suggests that circulation is chronically relaxed for at least 6 mo in space.
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Affiliation(s)
- B. Verheyden
- Laboratory Experimental Cardiology and Interdisciplinary Centre for Space Studies, University Hospital Gasthuisberg, Leuven, Belgium
| | - J. Liu
- Laboratory Experimental Cardiology and Interdisciplinary Centre for Space Studies, University Hospital Gasthuisberg, Leuven, Belgium
| | - F. Beckers
- Laboratory Experimental Cardiology and Interdisciplinary Centre for Space Studies, University Hospital Gasthuisberg, Leuven, Belgium
| | - A. E. Aubert
- Laboratory Experimental Cardiology and Interdisciplinary Centre for Space Studies, University Hospital Gasthuisberg, Leuven, Belgium
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18
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Eckberg DL, Halliwill JR, Beightol LA, Brown TE, Taylor JA, Goble R. Human vagal baroreflex mechanisms in space. J Physiol 2010; 588:1129-38. [PMID: 20156846 DOI: 10.1113/jphysiol.2009.186650] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Although astronauts' cardiovascular function is normal while they are in space, many have altered haemodynamic responses to standing after they return to Earth, including inordinate tachycardia, orthostatic hypotension, and uncommonly, syncope. Simulated microgravity impairs vagal baroreceptor-cardiac reflex function and causes orthostatic hypotension. Actual microgravity, however, has been shown to either increase, or not change vagal baroreflex gain. In this study, we tested the null hypothesis that spaceflight does not impair human baroreflex mechanisms. We studied 11 American and two German astronauts before, during (flight days 2-8), and after two, 9- and 10-day space shuttle missions, with graded neck pressure and suction, to elicit sigmoid, vagally mediated carotid baroreflex R-R interval responses. Baseline systolic pressures tended to be higher in space than on Earth (P = 0.015, repeated measures analysis of variance), and baseline R-R intervals tended to be lower (P = 0.049). Baroreceptor-cardiac reflex relations were displaced downward on the R-R interval axis in space. The average range of R-R interval responses to neck pressure changes declined from preflight levels by 37% on flight day 8 (P = 0.051), maximum R-R intervals declined by 14% (P = 0.003), and vagal baroreflex gain by 9% (P = 0.009). These measures returned to preflight levels by 7-10 days after astronauts returned to Earth. This study documents significant increases of arterial pressure and impairment of vagal baroreflex function in space. These results and results published earlier indicate that microgravity exposure augments sympathetic, and diminishes vagal cardiovascular influences.
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Affiliation(s)
- Dwain L Eckberg
- Department of Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center and Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA.
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19
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Nour S, Wu G, Zhensheng Z, Chachques JC, Carpentier A, Payen D. The forgotten driving forces in right heart failure: new concept and device. Asian Cardiovasc Thorac Ann 2010; 17:525-30. [PMID: 19917800 DOI: 10.1177/0218492309348638] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Right heart failure is a frequent hemodynamic disturbance in pediatric cardiac patients. Besides inotropic and chronotropic drugs, fluid administration and inhaled nitric oxide, right ventricular mechanical assistance remains difficult to perform. A circulatory assist device adapted for the right heart biophysics and physiology might be more efficient. MATERIALS AND METHODS We are developing a prototype of a non-invasive cardiac assist device (CAD) for neonates and pediatrics. It is based on a pulsatile suit device covering and affecting all territories of the right heart circuit. It will be tested in a neonatal animal model of right ventricular (RV) failure. Experimental models will be matched and compared with control and sham groups. Expected results would be immediate hemodynamic improvement due to synchronized diastolic reduction of stagnant venous capacitance, increasing preload and contractility. On long term, increased shear stress with changing intrathoracic pressure in a phasic way would improve and remodel the pulmonary circulation. Future studies will be focused on: hemodynamic, biochemistry, endothelium function test, and angiogenesis. COMMENTS A non-invasive CAD guarantees better hemodynamics and endothelial function preservation with low morbidity and mortality. This is a physiological approach, cost-effective method, and particularly interesting in neonates and pediatrics with RV failure.
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Affiliation(s)
- Sayed Nour
- Laboratory of Biosurgical Research, 96 rue Didot, 75014 Paris, France.
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20
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Hoffmann U. Results from recent spaceflight experiments (1). Respir Physiol Neurobiol 2009; 169 Suppl 1:S4-5. [DOI: 10.1016/j.resp.2009.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/04/2009] [Accepted: 05/05/2009] [Indexed: 10/20/2022]
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21
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Adaptation of heart rate and blood pressure to short and long duration space missions. Respir Physiol Neurobiol 2009; 169 Suppl 1:S13-6. [DOI: 10.1016/j.resp.2009.03.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 03/16/2009] [Accepted: 03/21/2009] [Indexed: 11/18/2022]
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22
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Prolonged head down bed rest-induced inactivity impairs tonic autonomic regulation while sparing oscillatory cardiovascular rhythms in healthy humans. J Hypertens 2009; 27:551-61. [PMID: 19262409 DOI: 10.1097/hjh.0b013e328322ca2f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Physical inactivity represents a major risk for cardiovascular disorders, such as hypertension, myocardial infarction or sudden death; however, underlying mechanisms are not clearly elucidated. Clinical and epidemiological investigations suggest, beyond molecular changes, the possibility of an induced impairment in autonomic cardiovascular regulation. However, this hypothesis has not been tested directly. METHODS Accordingly, we planned a study with noninvasive, minimally intrusive, techniques on healthy volunteers. Participants were maintained for 90 days strictly in bed, 24 h a day, in head-down (-6 degrees ) position (HDBR). Physical activity was thus virtually abolished for the entire period of HDBR. We examined efferent muscle sympathetic nerve activity, as a measure of vascular sympathetic control, baroreceptor reflex sensitivity, heart rate variability (assessing cardiovagal regulation), RR and systolic arterial pressure and low-frequency and high-frequency normalized components (as a window on central oscillatory regulation). Measures were obtained at rest and during simple maneuvers (moderate handgrip, lower body negative pressure and active standing) to assess potential changes in autonomic cardiovascular responsiveness to standard stimuli and the related oscillatory profiles. RESULTS HDBR transiently reduced muscle sympathetic nerve activity, RR, heart rate variability and baroreceptor reflex sensitivity late during HDBR or early during the recovery phase. Conversely, oscillatory profiles of RR and systolic arterial pressure variability were maintained throughout. Responsiveness to test stimuli was also largely maintained. CONCLUSION Prolonged inactivity as induced by HDBR in healthy volunteers reduces both cardiovagal and vascular sympathetic regulation, while largely maintaining peripheral responsiveness to standardized stimuli and sparing the functional structure of central oscillatory cardiovascular regulation.
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Karemaker JM, Berecki-Gisolf J. 24-h blood pressure in Space: The dark side of being an astronaut. Respir Physiol Neurobiol 2009; 169 Suppl 1:S55-8. [PMID: 19481180 DOI: 10.1016/j.resp.2009.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 05/18/2009] [Accepted: 05/20/2009] [Indexed: 11/17/2022]
Abstract
Inflight 24-h profiles of blood pressure (BP) and heart rate (HR) were recorded in 2 ESA-astronauts by automatic upper arm cuff measurements. In one astronaut this was combined with Portapres continuous finger blood pressure recordings. It was the intention to contrast the latter to 24-h recordings in an earlier Head-Down-Tilted (HDT) bed rest study [Voogel, A.J., Stok, W.J., Pretorius, P.J., Van Montfrans, G.A., Langewouters, G.J., Karemaker, J.M., 1997. Circadian blood pressure and systemic haemodynamics during 42 days of 6 degrees head-down tilt. Acta Physiol. Scand. 161, pp. 71-80]. BP-levels in Space were not very much changed from preflight; the circadian BP-rhythm seemed dampened. Only daytime diastolic pressures (both subjects) and nighttime HR (one subject) were significantly lower in Space. However, compared to the effect of a control tilt manoeuvre on the ground, even lower BP values might have been expected. Striking were the BP- and HR-surges during the working days in Space, often related to stressful moments like live appearances on public TV. Systemic vascular resistance (SVR) dropped during the night, unlike HDT. Thus, actual spaceflight refuted our earlier findings in HDT both for BP-levels and for daytime to nighttime changes. The combined observations lead to the hypothesis that short-lasting spaceflight may induce strong psychological stress in astronauts. When interpreting space-physiological observations this must be taken into account.
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Affiliation(s)
- John M Karemaker
- Department of Systems Physiology, Academic Medical Center at the University of Amsterdam, The Netherlands.
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24
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Moffitt JA, Grippo AJ, Beltz TG, Johnson AK. Hindlimb unloading elicits anhedonia and sympathovagal imbalance. J Appl Physiol (1985) 2008; 105:1049-59. [PMID: 18635876 DOI: 10.1152/japplphysiol.90535.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hindlimb-unloaded (HU) rat model elicits cardiovascular deconditioning and simulates the physiological adaptations to microgravity or prolonged bed rest in humans. Although psychological deficits have been documented following bed rest and spaceflight in humans, few studies have explored the psychological effects of cardiovascular deconditioning in animal models. Given the bidirectional link established between cardiac autonomic imbalance and psychological depression in both humans and in animal models, we hypothesized that hindlimb unloading would elicit an alteration in sympathovagal tone and behavioral indexes of psychological depression. Male, Sprague-Dawley rats confined to 14 days of HU displayed anhedonia (a core feature of human depression) compared with casted control (CC) animals evidenced by reduced sucrose preference (CC: 81 +/- 2.9% baseline vs. HU: 58 +/- 4.5% baseline) and reduced (rightward shift) operant responding for rewarding electrical brain stimulation (CC: 4.4 +/- 0.3 muA vs. 7.3 +/- 1.0 muA). Cardiac autonomic blockade revealed elevated sympathetic [CC: -54 +/- 14.1 change in (Delta) beats/min vs. HU: -118 +/- 7.6 Delta beats/min] and reduced parasympathetic (CC: 45 +/- 11.8 Delta beats/min vs. HU: 8 +/- 7.3 Delta beats/min) cardiac tone in HU rats. Heart rate variability was reduced (CC: 10 +/- 1.4 ms vs. HU: 7 +/- 0.7 ms), and spectral analysis of blood pressure indicated loss of total, low-, and high-frequency power, consistent with attenuated baroreflex function. These data indicate that cardiovascular deconditioning results in sympathovagal imbalance and behavioral signs consistent with psychological depression. These findings further elucidate the pathophysiological link between cardiovascular diseases and affective disorders.
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Affiliation(s)
- Julia A Moffitt
- Department of Psychology, The University of Iowa, Iowa City, IA 52242-1407, USA.
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Verheyden B, Beckers F, Couckuyt K, Liu J, Aubert AE. Respiratory modulation of cardiovascular rhythms before and after short-duration human spaceflight. Acta Physiol (Oxf) 2007; 191:297-308. [PMID: 17784903 DOI: 10.1111/j.1748-1716.2007.01744.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM Astronauts commonly return from space with altered short-term cardiovascular dynamics and blunted baroreflex sensitivity. Although many studies have addressed this issue, post-flight effects on the dynamic circulatory control remain incompletely understood. It is not clear how long the cardiovascular system needs to recover from spaceflight as most post-flight investigations only extended between a few days and 2 weeks. METHODS In this study, we examined the effect of short-duration spaceflight (1-2 weeks) on respiratory-mediated cardiovascular rhythms in five cosmonauts. Two paced-breathing protocols at 6 and 12 breaths min(-1) were performed in the standing and supine positions before spaceflight, and after 1 and 25 days upon return. Dynamic baroreflex function was evaluated by transfer function analysis between systolic pressure and the RR intervals. RESULTS Post-flight orthostatic blood pressure control was preserved in all cosmonauts. In the standing position after spaceflight there was an increase in heart rate (HR) of approx. 20 beats min(-1) or more. Averaged for all five cosmonauts, respiratory sinus dysrhythmia and transfer gain reduced to 40% the day after landing, and had returned to pre-flight levels after 25 days. Low-frequency gain decreased from 6.6 (3.4) [mean (SD)] pre-flight to 3.9 (1.6) post-flight and returned to 5.7 (1.3) ms mmHg(-1) after 25 days upon return to Earth. Unlike alterations in the modulation of HR, blood pressure dynamics were not significantly different between pre- and post-flight sessions. CONCLUSION Our results indicate that short-duration spaceflight reduces respiratory modulation of HR and decreases cardiac baroreflex gain without affecting post-flight arterial blood pressure dynamics. Altered respiratory modulation of human autonomic rhythms does not persist until 25 days upon return to Earth.
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Affiliation(s)
- B Verheyden
- Laboratory of Experimental Cardiology, University Hospital Gasthuisberg, Leuven, Belgium.
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Baevsky RM, Baranov VM, Funtova II, Diedrich A, Pashenko AV, Chernikova AG, Drescher J, Jordan J, Tank J. Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station. J Appl Physiol (1985) 2007; 103:156-61. [PMID: 17446414 DOI: 10.1152/japplphysiol.00137.2007] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Impaired autonomic control represents a cardiovascular risk factor during long-term spaceflight. Little has been reported on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) during and after prolonged spaceflight. We tested the hypothesis that cardiovascular control remains stable during prolonged spaceflight. Electrocardiography, photoplethysmography, and respiratory frequency (RF) were assessed in eight male cosmonauts (age 41–50 yr, body-mass index of 22–28 kg/m2) during long-term missions (flight lengths of 162–196 days). Recordings were made 60 and 30 days before the flight, every 4 wk during flight, and on days 3 and 6 postflight during spontaneous and controlled respiration. Orthostatic testing was performed pre- and postflight. RF and BP decreased during spaceflight ( P < 0.05). Mean HR and HRV in the low- and high-frequency bands did not change during spaceflight. However, the individual responses were different and correlated with preflight values. Pulse-wave transit time decreased during spaceflight ( P < 0.05). HRV reached during controlled respiration (6 breaths/min) decreased in six and increased in one cosmonaut during flight. The most pronounced changes in HR, BP, and HRV occurred after landing. The decreases in BP and RF combined with stable HR and HRV during flight suggest functional adaptation rather than pathological changes. Pulse-wave transit time shortening in our study is surprising and may reflect cardiac output redistribution in space. The decrease in HRV during controlled respiration (6 breaths/min) indicates reduced parasympathetic reserve, which may contribute to postflight disturbances.
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Mizuno K, Inoue Y, Tanaka H, Komada Y, Saito H, Mishima K, Shirakawa S. Heart rate variability under acute simulated microgravity during daytime waking state and nocturnal sleep: Comparison of horizontal and 6° head-down bed rest. Neurosci Lett 2005; 383:115-20. [PMID: 15936522 DOI: 10.1016/j.neulet.2005.03.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2004] [Revised: 03/28/2005] [Accepted: 03/29/2005] [Indexed: 11/22/2022]
Abstract
This study examined the acute effect of cephalad fluid shift under simulated microgravity on heart rate variability (HRV) during both daytime waking state and nocturnal sleep. Seven healthy male volunteers (21-31 years) underwent a series of experiments involving 6 degrees head-down bed rest (HD) for 3 days. A control experiment on the same subjects was conducted under horizontal bed rest (HZ) in the same series. HRV from electrocardiogram signals was periodically calculated by the MemCalc method during daytime on the first and second days of both conditions. Nocturnal sleep on the first night of bed rest was monitored by polysomnography. HRV during stage 2 sleep and REM sleep were assessed in the former and latter halves of the sleep period time. Nocturnal sleep architecture under both conditions was normal, but a slight decrease in stage 4 sleep and an increase in the number of arousals occurred under HD. On both the first and second days, HRV during the daytime did not differ between HZ and HD. In contrast, high frequency components in HRV during sleep stage 2 were significantly higher in the latter half of sleep under HD than under HZ, although there were no differences in the ratio of low frequency to high frequency components during both stage 2 and the REM stage between the conditions. These results suggest that the acute effect of the cephalad fluid shift on cardiac autonomic nervous activity might be affected by the sleep/wake state modulating the dominance between sympathetic and parasympathetic nervous activity.
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Affiliation(s)
- Koh Mizuno
- Geriatric Mental Health, National Institute of Mental Health, National Center of Neurology and Psychiatry, Ichikawa, Chiba, Japan.
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Mueller PJ, Foley CM, Hasser EM. Hindlimb unloading alters nitric oxide and autonomic control of resting arterial pressure in conscious rats. Am J Physiol Regul Integr Comp Physiol 2005; 289:R140-7. [PMID: 15761183 DOI: 10.1152/ajpregu.00820.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
After periods of microgravity or bed rest, individuals often exhibit reduced Vo(2 max), hypovolemia, cardiac and vascular effects, and autonomic dysfunction. Recently, alterations in expression of vascular and central nervous system NO synthase (NOS) have been observed in hindlimb-unloaded (HU) rats, a model used to simulate physiological effects of microgravity or bed rest. We examined the effects of 14 days of hindlimb unloading on hemodynamic responses to systemic NOS inhibition in conscious control and HU rats. Because differences in NO and autonomic regulation might occur after hindlimb unloading, we also evaluated potential differences in resting autonomic tone and effects of NOS inhibition after autonomic blockade. Administration of nitro-L-arginine methyl ester (L-NAME; 20 mg/kg iv) increased mean arterial pressure (MAP) to similar levels in control and HU rats. However, the change in MAP in response to L-NAME was less in HU rats, that had an elevated baseline MAP. In separate experiments, atropine (1 mg/kg iv) increased heart rate (HR) in control but not HU rats. Subsequent administration of the ganglionic blocker hexamethonium (30 mg/kg iv) decreased MAP and HR to a greater extent in HU rats. Administration of L-NAME after autonomic blockade increased MAP in both groups to a greater extent compared with intact conditions. However, the pressor response to L-NAME was still reduced in HU rats. These data suggest that hindlimb unloading in rats reduces peripheral NO as well as cardiac parasympathetic tone. Along with elevations in sympathetic tone, these effects likely contribute to alterations in vascular control and changes in autonomic reflex function following spaceflight or bed rest.
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Affiliation(s)
- Patrick J Mueller
- Dalton Cardiovascular Research Center, Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211-3300, USA.
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Jurysta F, van de Borne P, Migeotte PF, Dumont M, Lanquart JP, Degaute JP, Linkowski P. A study of the dynamic interactions between sleep EEG and heart rate variability in healthy young men. Clin Neurophysiol 2004; 114:2146-55. [PMID: 14580613 DOI: 10.1016/s1388-2457(03)00215-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We investigated the interactions between heart rate variability and sleep electroencephalogram power spectra. METHODS Heart rate and sleep electroencephalogram signals were recorded in 8 healthy young men. Spectral analysis was applied to electrocardiogram and electroencephalogram recordings. Spectral components of RR intervals were studied across sleep stages. The cross-spectrum maximum was determined as well as coherencies, gains and phase shifts between normalized high frequency of RR intervals and all electroencephalographic frequency bands, calculated over the first 3 NREM-REM cycles. RESULTS RR intervals increased from awake to NREM and decreased during REM. Normalized low frequency decreased from awake to NREM and increased during REM while normalized high frequency evolved conversely. Low to high frequency ratio developed in opposition to RR intervals. Coherencies between normalized high frequency and power spectra were high for all bands. The gain was highest for delta band. Phase shift between normalized high frequency and delta differed from zero and modifications in normalized high frequency preceded changes in delta by 41+/-14 degrees. CONCLUSIONS Our study demonstrates that: (1) all electroencephalographic power bands are linked to normalized high frequency; (2) modifications in cardiac vagal activity show predominantly parallel changes and precede changes in delta band by a phase shift corresponding to a lead of 12+/-5 min.
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Affiliation(s)
- F Jurysta
- Sleep Laboratory, Department of Psychiatry, Erasme Academic Hospital, Free University of Brussels, 1070 Brussels, Belgium.
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