Echocardiographic Evaluation of the Cardiovascular Effects of Short‐Duration Spaceflight

Mulvagh, Sharon L.; Charles, John B.; Riddle, Jeanne M.; Rehbein, Tracy L.; Bungo, Michael W.

doi:10.1002/j.1552-4604.1991.tb03666.x

Cited by 63 publications

(42 citation statements)

References 5 publications

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“…The reduction in cardiac size that has been previously observed, initially after both short-term HDT (Hung et al 1983;Levine et al 1997) and space¯ight (Mulvagh et al 1991), and also after long-term space¯ight (Henry et al 1977), appears to prevail for an extended period after HDT of the present duration. As re¯ected by the SV when supine from day R + 2 onwards, there appeared to be only a limited recovery.…”

Section: Discussionmentioning

confidence: 51%

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Sundblad¹,

Spaak²,

Linnarsson³

2000

European Journal of Applied Physiology

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Seven healthy men performed steady-state dynamic leg exercise at 50 W in supine and upright postures, before (control) and repeatedly after 42 days of strict head-down tilt (HDT) (-6 degrees) bedrest. Steady-state heart rate (fc), mean arterial blood pressure, cardiac output (Qc), and stroke volume (SV) were recorded. The following data changed significantly from control values. The fc was elevated in both postures at least until 12 days, but not at 32 days after bedrest. Immediately after HDT, SV and Qc were decreased by 25 (SEM 3)% and 19 (SEM 3)% in supine, and by 33 (SEM 5)% and 20 (SEM 3)% in upright postures, respectively. Within 2 days there was a partial recovery of SV in the upright but not in the supine posture. The SV and Qc during supine exercise remained significantly decreased for at least a month. Submaximal oxygen uptake did not change after HDT. We concluded that the cardiovascular response to exercise after prolonged bedrest was impaired for so long that it suggested that structural cardiac changes had developed during the HDT period.

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Section: Discussionmentioning

confidence: 51%

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Sundblad¹,

Spaak²,

Linnarsson³

2000

European Journal of Applied Physiology

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“…Spaceflight or its ground analog -HDBR -are characterized by diminished cardiac function and mass [15,16] . The initial trigger to this effect is the fluid shift from the lower to the upper body that results in upper body blood volume expansion.…”

Section: Cardiovascular Controlmentioning

confidence: 99%

Space, Gravity and the Physiology of Aging: Parallel or Convergent Disciplines? A Mini-Review

Vernikos

Schneider²

2009

Gerontology

167

109

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The abnormal physiology that manifests itself in healthy humans during their adaptation to the microgravity of space has all the features of accelerated aging. The mechano-skeletal and vestibulo-neuromuscular stimuli which are below threshold in space, result in an overall greater than 10-fold more rapid onset and time course of muscle and bone atrophy in space and the development of balance and coordination problems on return to Earth than occur with aging. Similarly, the loss of functional capacity of the cardiovascular system that results in space and continuous bed rest is over 10 times faster than in the course of aging. Deconditioning in space from gravity deprivation has brought attention to the medical hazards of deconditioning on Earth from gravity withdrawal as in sedentary aging. Though seemingly reversible after periods of 6 months in space or its ground analog of bed rest, it remains to be seen whether that will be so after longer exposures. Both adaptation to space and aging do not merely parallel but converge as disorders of mechanotransduction. Like spaceflight, its analog bed rest telescopes the changes observed with aging and serves as a useful clinical model for the study of age-related deconditioning. The convergence of the disciplines of aging, along with gravitational and space physiology is advancing the understanding and prevention of modern lifestyle medical disorders.

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“…Expression of sarcoplasmic reticulum Ca 2ϩ ATPase 2 and ryanodine 3 receptor mRNA was unaffected by HU, while ryanodine 2 receptor mRNA and protein expression were diminished in mesenteric arteries from HU rats. These data suggest that HU-induced and microgravity-associated orthostatic intolerance may be due, in part, to an attenuated vasoconstrictor responsiveness of mesenteric resistance arteries resulting from a diminished ryanodine 2 receptor Ca 2ϩ release mechanism.hindlimb unloading; vasoconstrictor responsiveness FOLLOWING EXPOSURE TO WEIGHTLESSNESs, many astronauts experience postflight orthostatic hypotension (6, 52) due, in part, to a diminished ability of the cardiovascular system to rapidly elevate peripheral vascular resistance (PVR) (1,2,8,36,52,53). It has been proposed that the diminished ability to elevate PVR following spaceflight may result from altered function of the afferent limb of the baroreceptors, central integration, sympathetic efferents, or end-organ responsiveness to sympathetic stimulation (8).…”

mentioning

confidence: 99%

“…hindlimb unloading; vasoconstrictor responsiveness FOLLOWING EXPOSURE TO WEIGHTLESSNESs, many astronauts experience postflight orthostatic hypotension (6, 52) due, in part, to a diminished ability of the cardiovascular system to rapidly elevate peripheral vascular resistance (PVR) (1,2,8,36,52,53). It has been proposed that the diminished ability to elevate PVR following spaceflight may result from altered function of the afferent limb of the baroreceptors, central integration, sympathetic efferents, or end-organ responsiveness to sympathetic stimulation (8).…”

mentioning

confidence: 99%

Simulated microgravity alters rat mesenteric artery vasoconstrictor dynamics through an intracellular Ca²⁺release mechanism

Colleran

Behnke

Wilkerson

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Colleran PN, Behnke BJ, Wilkerson MK, Donato AJ, Delp MD. Simulated microgravity alters rat mesenteric artery vasoconstrictor dynamics through an intracellular Ca 2ϩ release mechanism. Am J Physiol Regul Integr Comp Physiol 294: R1577-R1585, 2008. First published March 19, 2008 doi:10.1152/ajpregu.00084.2008.-Previous work has shown that orthostatic hypotension associated with cardiovascular deconditioning results from inadequate peripheral vasoconstriction. We used the hindlimb-unloaded (HU) rat in this study as a model to induce cardiovascular deconditioning. The purpose of this study was to test the hypothesis that 14 days of HU diminishes vasoconstrictor responsiveness of mesenteric resistance arteries. Mesenteric resistance arteries from control (n ϭ 43) and HU (n ϭ 44) rats were isolated, cannulated, and pressurized to 108 cm H2O for in vitro experimentation. Myogenic (intralumenal pressure ranging from 30 to 180 cm H2O), KCl (2-100 mM), norepinephrine (NE, 10 Ϫ9 -10 Ϫ4 M) and caffeine (1-20 mM) induced vasoconstriction, as well as the temporal dynamics of vasoconstriction to NE, were determined. The active myogenic and passive pressure responses were unaltered by HU when pressures remained within physiological range. However, vasoconstrictor responses to KCl, NE, and caffeine were diminished by HU, as well as the rate of constriction to NE (C, 14.8 Ϯ 3.6 m/s vs. HU 7.6 Ϯ 1.8 m/s). Expression of sarcoplasmic reticulum Ca 2ϩ ATPase 2 and ryanodine 3 receptor mRNA was unaffected by HU, while ryanodine 2 receptor mRNA and protein expression were diminished in mesenteric arteries from HU rats. These data suggest that HU-induced and microgravity-associated orthostatic intolerance may be due, in part, to an attenuated vasoconstrictor responsiveness of mesenteric resistance arteries resulting from a diminished ryanodine 2 receptor Ca 2ϩ release mechanism.hindlimb unloading; vasoconstrictor responsiveness FOLLOWING EXPOSURE TO WEIGHTLESSNESs, many astronauts experience postflight orthostatic hypotension (6, 52) due, in part, to a diminished ability of the cardiovascular system to rapidly elevate peripheral vascular resistance (PVR) (1,2,8,36,52,53). It has been proposed that the diminished ability to elevate PVR following spaceflight may result from altered function of the afferent limb of the baroreceptors, central integration, sympathetic efferents, or end-organ responsiveness to sympathetic stimulation (8). Evidence for end-organ (vascular) hyporesponsiveness has been provided by Whitson et al. (54) and Levine et al. (27), who reported no difference in preflight vs. postflight PVR during orthostasis despite higher postflight levels of plasma catecholamine concentration and muscle sympathetic nerve activity. Similar reductions in vasoconstrictor responsiveness have been reported by investigators using prolonged bedrest (44, 46). Therefore, evidence suggests endorgan responsiveness to vasoconstrictor stimuli is diminished in humans following microgravity and bedrest deconditioning.In addition, orthostatic intol...

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Echocardiographic Evaluation of the Cardiovascular Effects of Short‐Duration Spaceflight

Cited by 63 publications

References 5 publications

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Space, Gravity and the Physiology of Aging: Parallel or Convergent Disciplines? A Mini-Review

Simulated microgravity alters rat mesenteric artery vasoconstrictor dynamics through an intracellular Ca²⁺release mechanism

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Echocardiographic Evaluation of the Cardiovascular Effects of Short‐Duration Spaceflight

Cited by 63 publications

References 5 publications

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Cardiovascular responses to upright and supine exercise in humans after 6 weeks of head-down tilt (−6°)

Space, Gravity and the Physiology of Aging: Parallel or Convergent Disciplines? A Mini-Review

Simulated microgravity alters rat mesenteric artery vasoconstrictor dynamics through an intracellular Ca2+release mechanism

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Simulated microgravity alters rat mesenteric artery vasoconstrictor dynamics through an intracellular Ca²⁺release mechanism