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Desai SA, Mirza UA, Mueller PJ. Influence of sex and sedentary conditions on sympathetic burst characteristics in prepubertal, postpubertal, and young adult rats. J Appl Physiol (1985) 2024; 136:1170-1181. [PMID: 38511214 DOI: 10.1152/japplphysiol.00649.2023] [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: 09/08/2023] [Revised: 03/07/2024] [Accepted: 03/15/2024] [Indexed: 03/22/2024] Open
Abstract
Recent evidence indicates that sex-based differences in cardiovascular disease (CVD) begin early in life, particularly when associated with risk factors such as a sedentary lifestyle. CVD is associated with elevated sympathetic nerve activity (SNA), quantified as increased SNA burst activity in humans. Whether burst characteristics are influenced by sex or sedentary conditions at younger ages is unknown. The purpose of our study is to compare SNA bursts in active and sedentary female and male rats at ages including prepuberty and young adulthood. We hypothesized that burst characteristics and blood pressure are higher under sedentary conditions and lower in female rats compared with males. We analyzed splanchnic SNA (SpSNA) recordings from Inactin-anesthetized male and female rats at 4-, 8-, and 16-wk of age. Physically active and sedentary rats were each housed in separate, environmentally controlled chambers where physically active rats had free access to an in-cage running wheel. Sympathetic bursts were obtained by rectifying and integrating the raw SpSNA signal. Burst frequency, burst height, and burst width were calculated using the Peak Parameters extension in LabChart. Our results showed that sedentary conditions produced a greater burst width in 8- and 16-wk-old rats compared with 4-wk-old rats in both males and females (P < 0.001 for both). Burst frequency and incidence were both higher in 16-wk-old males compared with 16-wk-old females (P < 0.001 for both). Our results suggest that there are sedentary lifestyle- and sex-related mechanisms that impact sympathetic regulation of blood pressure at ages that range from prepuberty into young adulthood.NEW & NOTEWORTHY The mechanisms of decreased incidence of cardiovascular disease (CVD) in reproductive-age women compared with age-matched men are unknown. The strong association between elevated sympathetic activity and CVD led us to characterize splanchnic sympathetic bursts in female and male rats. Prepubescent males and females exhibited narrower sympathetic bursts, whereas young adult males had higher resting burst frequency compared with age-matched females. Sex-based regulation of sympathetic activity suggests a need for sex-dependent therapeutic strategies to combat CVD.
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Affiliation(s)
- Shivansh A Desai
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Umme Aiman Mirza
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Patrick J Mueller
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States
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Lima-Silveira L, Martinez D, Hasser EM, Kline DD. Mechanisms Underlying Neuroplasticity in the Nucleus Tractus Solitarii Following Hindlimb Unloading in Rats. Neuroscience 2020; 449:214-227. [PMID: 33039526 DOI: 10.1016/j.neuroscience.2020.09.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/15/2020] [Accepted: 09/20/2020] [Indexed: 12/11/2022]
Abstract
Hindlimb unloading (HU) in rats induces cardiovascular deconditioning (CVD) analogous to that observed in individuals exposed to microgravity or bed rest. Among other physiological changes, HU rats exhibit autonomic imbalance and altered baroreflex function. Lack of change in visceral afferent activity that projects to the brainstem in HU rats suggests that neuronal plasticity within central nuclei processing cardiovascular afferents may be responsible for these changes in CVD and HU. The nucleus tractus solitarii (nTS) is a critical brainstem region for autonomic control and integration of cardiovascular reflexes. In this study, we used patch electrophysiology, live-cell calcium imaging and molecular methods to investigate the effects of HU on glutamatergic synaptic transmission and intrinsic properties of nTS neurons. HU increased the amplitude of monosynaptic excitatory postsynaptic currents and presynaptic calcium entry evoked by afferent tractus solitarii stimulus (TS-EPSC); spontaneous (s) EPSCs were unaffected. The addition of a NMDA receptor antagonist (AP5) reduced TS-EPSC amplitude and sEPSC frequency in HU but not control. Despite the increase in glutamatergic inputs, HU neurons were more hyperpolarized and exhibited intrinsic decreased excitability compared to controls. After block of ionotropic glutamatergic and GABAergic synaptic transmission (NBQX, AP5, Gabazine), HU neuronal membrane potential depolarized and neuronal excitability was comparable to controls. These data demonstrate that HU increases presynaptic release and TS-EPSC amplitude, which includes a NMDA receptor component. Furthermore, the decreased excitability and hyperpolarized membrane after HU are associated with enhanced GABAergic modulation. This functional neuroplasticity in the nTS may underly the CVD induced by HU.
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Affiliation(s)
- Ludmila Lima-Silveira
- Department of Biomedical Sciences, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA; Dalton Cardiovascular Research Center, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA.
| | - Diana Martinez
- Department of Biomedical Sciences, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA; Dalton Cardiovascular Research Center, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA.
| | - Eileen M Hasser
- Department of Biomedical Sciences, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA; Department of Medical Pharmacology and Physiology, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA; Dalton Cardiovascular Research Center, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA.
| | - David D Kline
- Department of Biomedical Sciences, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA; Dalton Cardiovascular Research Center, University of Missouri, 134 Research Park Dr., Columbia, MO 65211, USA.
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3
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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: 8] [Impact Index Per Article: 2.0] [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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Cortese F, Klokov D, Osipov A, Stefaniak J, Moskalev A, Schastnaya J, Cantor C, Aliper A, Mamoshina P, Ushakov I, Sapetsky A, Vanhaelen Q, Alchinova I, Karganov M, Kovalchuk O, Wilkins R, Shtemberg A, Moreels M, Baatout S, Izumchenko E, de Magalhães JP, Artemov AV, Costes SV, Beheshti A, Mao XW, Pecaut MJ, Kaminskiy D, Ozerov IV, Scheibye-Knudsen M, Zhavoronkov A. Vive la radiorésistance!: converging research in radiobiology and biogerontology to enhance human radioresistance for deep space exploration and colonization. Oncotarget 2018; 9:14692-14722. [PMID: 29581875 PMCID: PMC5865701 DOI: 10.18632/oncotarget.24461] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/31/2018] [Indexed: 12/12/2022] Open
Abstract
While many efforts have been made to pave the way toward human space colonization, little consideration has been given to the methods of protecting spacefarers against harsh cosmic and local radioactive environments and the high costs associated with protection from the deleterious physiological effects of exposure to high-Linear energy transfer (high-LET) radiation. Herein, we lay the foundations of a roadmap toward enhancing human radioresistance for the purposes of deep space colonization and exploration. We outline future research directions toward the goal of enhancing human radioresistance, including upregulation of endogenous repair and radioprotective mechanisms, possible leeways into gene therapy in order to enhance radioresistance via the translation of exogenous and engineered DNA repair and radioprotective mechanisms, the substitution of organic molecules with fortified isoforms, and methods of slowing metabolic activity while preserving cognitive function. We conclude by presenting the known associations between radioresistance and longevity, and articulating the position that enhancing human radioresistance is likely to extend the healthspan of human spacefarers as well.
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Affiliation(s)
- Franco Cortese
- Biogerontology Research Foundation, London, UK
- Department of Biomedical and Molecular Sciences, Queen's University School of Medicine, Queen's University, Kingston, Ontario, Canada
| | - Dmitry Klokov
- Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Andreyan Osipov
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
- State Research Center - Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Jakub Stefaniak
- Biogerontology Research Foundation, London, UK
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
| | - Alexey Moskalev
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Laboratory of Molecular Radiobiology and Gerontology, Institute of Biology of Komi Science Center of Ural Branch of Russian Academy of Sciences, Syktyvkar, Russia
- Engelhardt Institute of Molecular Biology of Russian Academy of Sciences, Moscow, Russia
| | - Jane Schastnaya
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
| | - Charles Cantor
- Boston University, Department of Biomedical Engineering, Boston, MA, USA
| | - Alexander Aliper
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
- Laboratory of Bioinformatics, D. Rogachev Federal Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Polina Mamoshina
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
- Computer Science Department, University of Oxford, Oxford, UK
| | - Igor Ushakov
- State Research Center - Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Moscow, Russia
| | - Alex Sapetsky
- State Research Center - Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Moscow, Russia
| | - Quentin Vanhaelen
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
| | - Irina Alchinova
- Laboratory of Physicochemical and Ecological Pathophysiology, Institute of General Pathology and Pathophysiology, Moscow, Russia
- Research Institute for Space Medicine, Federal Medical Biological Agency, Moscow, Russia
| | - Mikhail Karganov
- Laboratory of Physicochemical and Ecological Pathophysiology, Institute of General Pathology and Pathophysiology, Moscow, Russia
| | - Olga Kovalchuk
- Canada Cancer and Aging Research Laboratories, Ltd., Lethbridge, Alberta, Canada
- University of Lethbridge, Lethbridge, Alberta, Canada
| | - Ruth Wilkins
- Environmental and Radiation and Health Sciences Directorate, Health Canada, Ottawa, Ontario, Canada
| | - Andrey Shtemberg
- Laboratory of Extreme Physiology, Institute of Medical and Biological Problems RAS, Moscow, Russia
| | - Marjan Moreels
- Radiobiology Unit, Interdisciplinary Biosciences, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre, (SCK·CEN), Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Interdisciplinary Biosciences, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre, (SCK·CEN), Mol, Belgium
- Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - Evgeny Izumchenko
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
- The Johns Hopkins University, School of Medicine, Department of Otolaryngology, Head and Neck Cancer Research, Baltimore, MD, USA
| | - João Pedro de Magalhães
- Biogerontology Research Foundation, London, UK
- Integrative Genomics of Ageing Group, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - Artem V. Artemov
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
| | | | - Afshin Beheshti
- Wyle Laboratories, Space Biosciences Division, NASA Ames Research Center, Mountain View, CA, USA
- Division of Hematology/Oncology, Molecular Oncology Research Institute, Tufts Medical Center, Boston, MA, USA
| | - Xiao Wen Mao
- Department of Basic Sciences, Division of Biomedical Engineering Sciences (BMES), Loma Linda University, Loma Linda, CA, USA
| | - Michael J. Pecaut
- Department of Basic Sciences, Division of Biomedical Engineering Sciences (BMES), Loma Linda University, Loma Linda, CA, USA
| | - Dmitry Kaminskiy
- Biogerontology Research Foundation, London, UK
- Deep Knowledge Life Sciences, London, UK
| | - Ivan V. Ozerov
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
- State Research Center - Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Moscow, Russia
| | | | - Alex Zhavoronkov
- Biogerontology Research Foundation, London, UK
- Insilico Medicine, Inc., Emerging Technology Centers, Johns Hopkins University, Baltimore, MD, USA
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Kitazawa T, Kitazawa K. Prolonged bed rest impairs rapid CPI-17 phosphorylation and contraction in rat mesenteric resistance arteries to cause orthostatic hypotension. Pflugers Arch 2017; 469:1651-1662. [PMID: 28717991 DOI: 10.1007/s00424-017-2031-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 07/03/2017] [Accepted: 07/09/2017] [Indexed: 02/07/2023]
Abstract
Prolonged bed rest (PBR) causes orthostatic hypotension (OH). Rapid constriction of splanchnic resistance arteries in response to a sudden increase in sympathetic tone contributes to the recovery of orthostatic arterial pressure upon standing. However, the molecular mechanism of PBR-induced dysfunction in arterial constriction is not fully understood. Previously, we showed that CPI-17, a regulatory protein for myosin phosphatase, mediates α1A-adrenergic receptor-induced rapid contraction of small mesenteric arteries. Here, we tested whether PBR associated with OH affects the α1-adrenergic receptor-induced CPI-17 signaling pathway in mesenteric arteries using rats treated by head-down tail-suspension hindlimb unloading (HDU), an experimental OH model. In normal anesthetized rats, mean arterial pressure (MAP) rapidly reduced upon 90° head-up tilt from supine position and then immediately recovered without change in heart rate, suggesting a rapid arterial constriction. On the other hand, after a 4-week HDU treatment, the fast orthostatic MAP recovery failed for 1 min. Alpha1A subtype-specific antagonist suppressed the orthostatic MAP recovery with a small decrease in basal blood pressure, whereas non-specific α1-antagonist prazosin strongly reduced both basal MAP and orthostatic recovery. The HDU treatment resulted in 68% reduction in contraction in parallel with 83% reduction in CPI-17 phosphorylation in denuded mesenteric arteries 10 s after α1-agonist stimulation. The treatment with either Ca2+-release channel opener or PKC inhibitor mimicked the deficiency in HDU arteries. These results suggest that an impairment of the rapid PKC/CPI-17 signaling pathway downstream of α1A-adrenoceptors in peripheral arterial constriction, as an end organ of orthostatic blood pressure reflex, is associated with OH in prolonged bed rest patients.
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Affiliation(s)
- Toshio Kitazawa
- Boston Biomedical Research Institute, Watertown, MA, 02472, USA. .,Department of Molecular Physiology and Biophysics, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA, 19107, USA.
| | - Kazuyo Kitazawa
- Boston Biomedical Research Institute, Watertown, MA, 02472, USA
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Stewart JM, Suggs M, Merchant S, Sutton R, Terilli C, Visintainer P, Medow MS. Postsynaptic α1-Adrenergic Vasoconstriction Is Impaired in Young Patients With Vasovagal Syncope and Is Corrected by Nitric Oxide Synthase Inhibition. Circ Arrhythm Electrophysiol 2017; 9:CIRCEP.115.003828. [PMID: 27444639 DOI: 10.1161/circep.115.003828] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 06/15/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). During VVS, gravitational pooling excessively reduces central blood volume and cardiac output. In VVS, as in hemorrhage, impaired adrenergic vasoconstriction and venoconstriction result in hypotension. We hypothesized that impaired adrenergic responsiveness because of excess nitric oxide can be reversed by reducing nitric oxide. METHODS AND RESULTS We recorded cardiopulmonary dynamics in supine syncope patients and healthy volunteers (aged 15-27 years) challenged with a dose-response using the α1-agonist phenylephrine (PE), with and without the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, monoacetate salt (L-NMMA). Systolic and diastolic pressures among control and VVS were the same, although they increased after L-NMMA and saline+PE (volume and pressor control for L-NMMA). Heart rate was significantly reduced by L-NMMA (P<0.05) for control and VVS compared with baseline, but there was no significant difference in heart rate between L-NMMA and saline+PE. Cardiac output and splanchnic blood flow were reduced by L-NMMA for control and VVS (P<0.05) compared with baseline, while total peripheral resistance increased (P<0.05). PE dose-response for splanchnic flow and resistance were blunted for VVS compared with control after saline+PE, but enhanced after L-NMMA (P<0.001). Postsynaptic α1-adrenergic vasoconstrictive impairment was greatest in the splanchnic vasculature, and splanchnic blood flow was unaffected by PE. Forearm and calf α1-adrenergic vasoconstriction were unimpaired in VVS and unaffected by L-NMMA. CONCLUSIONS Impaired postsynaptic α1-adrenergic vasoconstriction in young adults with VVS can be corrected by nitric oxide synthase inhibition, demonstrated with our use of L-NMMA.
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Affiliation(s)
- Julian M Stewart
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
| | - Melissa Suggs
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Sana Merchant
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Richard Sutton
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Courtney Terilli
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Paul Visintainer
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Marvin S Medow
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
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7
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Stewart JM, Sutton R, Kothari ML, Goetz AM, Visintainer P, Medow MS. Nitric oxide synthase inhibition restores orthostatic tolerance in young vasovagal syncope patients. Heart 2017; 103:1711-1718. [PMID: 28501796 DOI: 10.1136/heartjnl-2017-311161] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/21/2017] [Accepted: 03/21/2017] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE Syncope is sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). We previously demonstrated impaired post-synaptic adrenergic responsiveness in young VVS patients was reversed by blocking nitric oxide synthase (NOS). We hypothesised that nitric oxide may account for reduced orthostatic tolerance in young recurrent VVS patients. METHODS We recorded haemodynamics in supine VVS and healthy volunteers (aged 15-27 years), challenged with graded lower body negative pressure (LBNP) (-15, -30, -45 mm Hg each for 5 min, then -60 mm Hg for a maximum of 50 min) with and without NOS inhibitor NG-monomethyl-L-arginine acetate (L-NMMA). Saline plus phenylephrine (Saline+PE) was used as volume and pressor control for L-NMMA. RESULTS Controls endured 25.9±4.0 min of LBNP during Saline+PE compared with 11.6±1.4 min for fainters (p<0.001). After L-NMMA, control subjects endured 24.8±3.2 min compared with 22.6±1.6 min for fainters. Mean arterial pressure decreased more in VVS patients during LBNP with Saline+PE (p<0.001) which was reversed by L-NMMA; cardiac output decreased similarly in controls and VVS patients and was unaffected by L-NMMA. Total peripheral resistance increased for controls but decreased for VVS during Saline+PE (p<0.001) but was similar following L-NMMA. Splanchnic vascular resistance increased during LBNP in controls, but decreased in VVS patients following Saline+PE which L-NMMA restored. CONCLUSIONS We conclude that arterial vasoconstriction is impaired in young VVS patients, which is corrected by NOS inhibition. The data suggest that both pre- and post-synaptic arterial vasoconstriction may be affected by nitric oxide.
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Affiliation(s)
- Julian M Stewart
- Departments of Pediatrics, New York Medical College, Valhalla, New York, USA.,Departments of Physiology, New York Medical College, Valhalla, New York, USA
| | - Richard Sutton
- The National Heart & Lung Institute, Imperial College, London, UK
| | - Mira L Kothari
- Departments of Pediatrics, New York Medical College, Valhalla, New York, USA
| | - Amanda M Goetz
- Departments of Pediatrics, New York Medical College, Valhalla, New York, USA
| | - Paul Visintainer
- Baystate Medical Center, University of Massachusetts School of Medicine 4, Springfield MA, USA
| | - Marvin Scott Medow
- Departments of Pediatrics, New York Medical College, Valhalla, New York, USA.,Departments of Physiology, New York Medical College, Valhalla, New York, USA
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8
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Brioche T, Pagano AF, Py G, Chopard A. Muscle wasting and aging: Experimental models, fatty infiltrations, and prevention. Mol Aspects Med 2016; 50:56-87. [PMID: 27106402 DOI: 10.1016/j.mam.2016.04.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 12/21/2022]
Abstract
Identification of cost-effective interventions to maintain muscle mass, muscle strength, and physical performance during muscle wasting and aging is an important public health challenge. It requires understanding of the cellular and molecular mechanisms involved. Muscle-deconditioning processes have been deciphered by means of several experimental models, bringing together the opportunities to devise comprehensive analysis of muscle wasting. Studies have increasingly recognized the importance of fatty infiltrations or intermuscular adipose tissue for the age-mediated loss of skeletal-muscle function and emphasized that this new important factor is closely linked to inactivity. The present review aims to address three main points. We first mainly focus on available experimental models involving cell, animal, or human experiments on muscle wasting. We next point out the role of intermuscular adipose tissue in muscle wasting and aging and try to highlight new findings concerning aging and muscle-resident mesenchymal stem cells called fibro/adipogenic progenitors by linking some cellular players implicated in both FAP fate modulation and advancing age. In the last part, we review the main data on the efficiency and molecular and cellular mechanisms by which exercise, replacement hormone therapies, and β-hydroxy-β-methylbutyrate prevent muscle wasting and sarcopenia. Finally, we will discuss a potential therapeutic target of sarcopenia: glucose 6-phosphate dehydrogenase.
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Affiliation(s)
- Thomas Brioche
- Université de Montpellier, INRA, UMR 866 Dynamique Musculaire et Métabolisme, Montpellier F-34060, France.
| | - Allan F Pagano
- Université de Montpellier, INRA, UMR 866 Dynamique Musculaire et Métabolisme, Montpellier F-34060, France
| | - Guillaume Py
- Université de Montpellier, INRA, UMR 866 Dynamique Musculaire et Métabolisme, Montpellier F-34060, France
| | - Angèle Chopard
- Université de Montpellier, INRA, UMR 866 Dynamique Musculaire et Métabolisme, Montpellier F-34060, France
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9
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Chowdhury P, Long A, Harris G, Soulsby ME, Dobretsov M. Animal model of simulated microgravity: a comparative study of hindlimb unloading via tail versus pelvic suspension. Physiol Rep 2013; 1:e00012. [PMID: 24303103 PMCID: PMC3831940 DOI: 10.1002/phy2.12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 05/04/2013] [Accepted: 05/20/2013] [Indexed: 12/21/2022] Open
Abstract
The aim of this study was to compare physiological effects of hindlimb suspension (HLS) in tail- and pelvic-HLS rat models to determine if severe stretch in the tail-HLS rats lumbosacral skeleton may contribute to the changes traditionally attributed to simulated microgravity and musculoskeletal disuse in the tail-HLS model. Adult male Sprague-Dawley rats divided into suspended and control-nonsuspended groups were subjected to two separate methods of suspension and maintained with regular food and water for 2 weeks. Body weights, food and water consumption, soleus muscle weight, tibial bone mineral density, random plasma insulin, and hindlimb pain on pressure threshold (PPT) were measured. X-ray analysis demonstrated severe lordosis in tail- but not pelvic-HLS animals. However, growth retardation, food consumption, and soleus muscle weight and tibial bone density (decreased relative to control) did not differ between two HLS models. Furthermore, HLS rats developed similar levels of insulinopenia and mechanical hyperalgesia (decreased PPT) in both tail- and pelvic-HLS groups. In the rat-to-rat comparisons, the growth retardation and the decreased PPT observed in HLS-rats was most associated with insulinopenia. In conclusion, these data suggest that HLS results in mild prediabetic state with some signs of pressure hyperalgesia, but lumbosacral skeleton stretch plays little role, if any, in these pathological changes.
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Affiliation(s)
- Parimal Chowdhury
- Department of Physiology and Biophysics, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
| | - Ashley Long
- Department of Physiology and Biophysics, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
| | - Gabrielle Harris
- Department of Physiology and Biophysics, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
| | - Michael E Soulsby
- Department of Physiology and Biophysics, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
| | - Maxim Dobretsov
- Department of Anesthesiology, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical SciencesLittle Rock, Arkansas, 72205
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10
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Zhang LF. Region-specific vascular remodeling and its prevention by artificial gravity in weightless environment. Eur J Appl Physiol 2013; 113:2873-95. [DOI: 10.1007/s00421-013-2597-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
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11
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Moffitt JA, Henry MK, Welliver KC, Jepson AJ, Garnett ER. Hindlimb unloading results in increased predisposition to cardiac arrhythmias and alters left ventricular connexin 43 expression. Am J Physiol Regul Integr Comp Physiol 2013; 304:R362-73. [PMID: 23302960 DOI: 10.1152/ajpregu.00391.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hindlimb unloading (HU) is a well-established animal model of cardiovascular deconditioning. Previous data indicate that HU results in cardiac sympathovagal imbalance. It is well established that cardiac sympathovagal imbalance increases the risk for developing cardiac arrhythmias. The cardiac gap junction protein connexin 43 (Cx43) is predominately expressed in the left ventricle (LV) and ensures efficient cell-to-cell electrical coupling. In the current study we wanted to test the hypothesis that HU would result in increased predisposition to cardiac arrhythmias and alter the expression and/or phosphorylation of LV-Cx43. Electrocardiographic data using implantable telemetry were obtained over a 10- to 14-day HU or casted control (CC) condition and in response to a sympathetic stressor using isoproterenol administration and brief restraint. The arrhythmic burden was calculated using a modified scoring system to quantify spontaneous and provoked arrhythmias. In addition, Western blot analysis was used to measure LV-Cx43 expression in lysates probed with antibodies directed against the total and an unphosphorylated form of Cx43 in CC and HU rats. HU resulted in a significantly greater total arrhythmic burden during the sympathetic stressor with significantly more ventricular arrhythmias occurring. In addition, there was increased expression of total LV-Cx43 observed with no difference in the expression of unphosphorylated LV-Cx43. Specifically, the increased expression of LV-Cx43 was consistent with the phosphorylated form. These data taken together indicate that cardiovascular deconditioning produced through HU results in increased predisposition to cardiac arrhythmias and increased expression of phosphorylated LV-Cx43.
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Affiliation(s)
- Julia A Moffitt
- Department of Physiology and Pharmacology, Des Moines University, 3200 Grand Ave., Des Moines, IA 50312, USA.
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12
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Cozza IC, Di Sacco THR, Mazon JH, Salgado MCO, Dutra SGV, Cesarino EJ, Souza HCD. Physical exercise improves cardiac autonomic modulation in hypertensive patients independently of angiotensin-converting enzyme inhibitor treatment. Hypertens Res 2011; 35:82-7. [DOI: 10.1038/hr.2011.162] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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13
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Zhang LF, Cheng JH, Liu X, Wang S, Liu Y, Lu HB, Ma J. Cardiovascular changes of conscious rats after simulated microgravity with and without daily −Gx gravitation. J Appl Physiol (1985) 2008; 105:1134-45. [DOI: 10.1152/japplphysiol.00184.2008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was designed to test the hypothesis that postsuspension cardiovascular manifestation in conscious rats after a medium-term (28-day) tail suspension (SUS) is hypertensive and tachycardiac and can be prevented by a countermeasure of daily 1-h dorsoventral (−G x) gravitation provided by standing (STD). To assess associated changes in cardiovascular regulation, blood pressure (BP) and heart rate (HR) variability were analyzed by spectral analysis computed by parametric autoregressive (AR) method and by nonlinear recurrence quantification analysis (RQA) and approximate entropy (ApEn) measure. The results showed that conscious SUS rats manifested hypertensive and tachycardiac response before and after being released from suspension compared with the controls, and the countermeasure of 1 h/day −G x prevented the hypertensive response. Auto- and cross-spectral analysis and transfer function analysis did not show significant changes in cardiovascular variability. However, SUS decreased the three RQA indexes [recurrence percentage (RC%), determinism percentage (DT%), and the longest diagonal line ( Lmax)] of systolic BP, whereas STD alleviated these changes. ApEn values of HR data sets were significantly higher in the SUS and SUS + STD groups compared with those of the control group before and after release from suspension. The present study has demonstrated that daily −G x for as short as 1 h is sufficient to prevent postsuspension cardiovascular alteration in conscious rats after a medium-term SUS. Nonlinear measures, but not spectral analysis, might provide promising data to estimate the overall changes in cardiovascular autonomic regulation due to microgravity exposure.
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14
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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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15
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Wecht JM, Weir JP, Goldstein DS, Krothe-Petroff A, Spungen AM, Holmes C, Bauman WA. Direct and reflexive effects of nitric oxide synthase inhibition on blood pressure. Am J Physiol Heart Circ Physiol 2007; 294:H190-7. [PMID: 17965289 DOI: 10.1152/ajpheart.00366.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Direct effects of vasoactive substances on blood pressure can be examined in individuals with tetraplegia due to disruption of descending spinal pathways to sympathetic preganglionic neurons, as cervical lesions interfere with baroreceptor reflex buffering of sympathetic outflow. In this study, we assessed effects of the nitric oxide synthase inhibitor nitro-L-arginine methyl ester (L-NAME) on mean arterial pressure, heart rate, and plasma norepinephrine concentrations in individuals with tetraplegia vs. effects shown in a neurologically intact control group. Seven individuals with tetraplegia and seven age-matched controls received, on separate visits and in the following order, placebo (30 ml normal saline) and 0.5, 1, 2, and 4 mg/kg L-NAME intravenously over 60 min. Supine hemodynamic data were collected, and blood was sampled at the end of each infusion and at 120, 180, and 240 min thereafter. L-NAME increased mean arterial pressure, and the relative increase was greater in the tetraplegia group than in the control group. Heart rate was reduced after L-NAME administration in both groups. L-NAME decreased plasma norepinephrine in the control group but not in the group with tetraplegia. These findings suggest that reflexive sympathoinhibition normally buffers the pressor response to nitric oxide synthase inhibition, an effect that is not evident in individuals with tetraplegia as a result of decentralized sympathetic vasomotor control.
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Affiliation(s)
- Jill M Wecht
- Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, 130 West Kingsbridge Rd., Bronx, NY 10468, USA.
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Mueller PJ, Foley CM, Heesch CM, Cunningham JT, Zheng H, Patel KP, Hasser EM. Increased nitric oxide synthase activity and expression in the hypothalamus of hindlimb unloaded rats. Brain Res 2006; 1115:65-74. [PMID: 16938283 DOI: 10.1016/j.brainres.2006.07.078] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 07/05/2006] [Accepted: 07/24/2006] [Indexed: 10/24/2022]
Abstract
Upon return from spaceflight or resumption of normal posture after bed rest, individuals often exhibit cardiovascular deconditioning. Although the mechanisms responsible for cardiovascular deconditioning have yet to be fully elucidated, alterations within the central nervous system have been postulated to be involved. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are important brain regions in control of sympathetic outflow and body fluid homeostasis. Nitric oxide (NO) modulates the activity of PVN and SON neurons, and alterations in NO transmission within these brain regions may contribute to symptoms of cardiovascular deconditioning. The purpose of the present study was to examine nitric oxide synthase (NOS) activity and expression in the PVN and SON of control and hindlimb unloaded (HU) rats, an animal model of cardiovascular deconditioning. The number of neurons exhibiting NOS activity as assessed by NADPH-diaphorase staining was significantly greater in the PVN but not SON of HU rats. Western blot analysis revealed that neuronal NOS (nNOS) but not endothelial NOS (eNOS) protein expression was higher in the PVN of HU rats. In the SON, there was a strong trend for an increase in nNOS (p=0.052) and a significant increase in eNOS expression in HU rats. Our results suggest that increased nNOS in the PVN contributes to autonomic and humoral alterations following cardiovascular deconditioning. In contrast, the functional significance of increases in nNOS and eNOS protein in the SON may be related to alterations in vasopressin release observed previously in HU rats.
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Affiliation(s)
- Patrick J Mueller
- Department of Biomedical Sciences, University of Missouri, Columbia, MO 65211-3300, USA.
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Mueller PJ, Sullivan MJ, Grindstaff RR, Cunningham JT, Hasser EM. Regulation of plasma vasopressin and renin activity in conscious hindlimb-unloaded rats. Am J Physiol Regul Integr Comp Physiol 2006; 291:R46-52. [PMID: 16469838 DOI: 10.1152/ajpregu.00622.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiovascular deconditioning occurs in astronauts after spaceflight or in individuals subjected to bed rest. It is characterized by an increased incidence of orthostatic intolerance. The mechanisms responsible for orthostatic intolerance are likely multifactorial and may include hypovolemia, autonomic dysfunction, and vascular and cardiac alterations. The arterial baroreflex is an important compensatory mechanism in the response to an orthostatic stress. In a previous study, we demonstrated that arterial baroreflex mediated sympathoexcitation was blunted in hindlimb-unloaded (HU) rats, a model of cardiovascular deconditioning. The arterial baroreflex also contributes to the regulation of vasoactive hormones including vasopressin and angiotensin II. In the present study, we tested the hypothesis that the neurohumoral response to hypotension is also attenuated in rats after 14 days of hindlimb unloading. To test this hypothesis, the vasodilator diazoxide (15 or 25 mg/kg) or saline (0.9%) was administered to produce hypotension or control conditions, respectively, in conscious HU and control rats. Plasma samples were collected and assayed for vasopressin and plasma renin activity (PRA). Diazoxide (25 mg/kg) produced significant increases in vasopressin and PRA compared with saline controls. HU rats exhibited significantly higher levels of vasopressin at rest and the increase in vasopressin levels during hypotension was enhanced by hindlimb unloading. Neither resting nor hypotension-induced PRA was altered by hindlimb unloading. These data suggest that although baroreflex-mediated sympathoexcitation is blunted by hindlimb unloading, hypotension-induced vasopressin release is enhanced and hypotension-induced PRA is unaffected. Increased circulating vasopressin may serve to compensate for blunted baroreflex regulation of sympathetic nervous activity produced by hindlimb unloading or may actually contribute to it.
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Affiliation(s)
- Patrick J Mueller
- Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, Missouri 65211-3300, USA.
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