Vasoconstrictor properties of rat aorta are diminished by hindlimb unweighting

Delp, Michael D.; Holder-Binkley, T.; Laughlin, M. Harold; Hasser, Eileen M.

doi:10.1152/jappl.1993.75.6.2620

Cited by 77 publications

(115 citation statements)

References 13 publications

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“…These results suggest that the NE-induced contraction of the rabbit basilar artery is induced mainly through activation of ␣ 1 -adrenergic receptors. Contractile responses to pheyleprine have been shown to decrease in the isolated aorta from rats exposed to hind-limb unloading [12], but not in leg vasculature of humans during HDT [18]. In the present study, phenylephrine-induced contraction of the rabbit basilar artery was smaller in the HDT group than in the control group, suggesting that activity of ␣ 1 -adrenergic receptors is related to the mechanism of decreased NE response.…”

Section: Discussioncontrasting

confidence: 51%

“…The effects of simulated microgravity on vascular responses to vasoactive agents have been investigated in rats exposed to hind-limb unloading or tail suspension. Delp and co-workers [12] showed that the contractile responses of isolated rat aorta to vasoconstrictors such as KCl, NE, phenylephrine, arginine vasopressin, and CaCl 2 were attenuated by hind-limb unloading. Purdy and colleagues [16] demonstrated that the NE-induced contraction of rat carotid and femoral arteries, as well as the aorta, was also reduced by 20 d of hind-limb unloading.…”

Section: Discussionmentioning

confidence: 99%

“…solution, NE, and vasopressin are attenuated after the tail suspension treatment [12]. In these studies, however, calcium mobilization caused by the vasoconstrictor agents has not been examined.…”

mentioning

confidence: 99%

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Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Ueda

Aoyama²,

Sasaka-Kitamura³

et al. 2001

JJP

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Section: Discussioncontrasting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

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Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Ueda

Aoyama²,

Sasaka-Kitamura³

et al. 2001

JJP

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“…In humans, impairments of macro-and microcirculation are also involved in this downregulation (1). On rodent models, studies were carried out and showed that simulated weightlessness has negative effects on structural (13) and functional properties (8,14) of vasculature. Another part of this downregulation is an alteration of equilibrium system (40).…”

Section: Why Countermeasure Had No Effect On Orthostatic Responsementioning

confidence: 99%

Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest

Coupé

Yuan

Demiot³

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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YH. Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest. Am J Physiol Regul Integr Comp Physiol 301: R1748 -R1754, 2011. First published September 7, 2011 doi:10.1152/ajpregu.00234.2011.-Whole body vibration with resistive exercise is a promising countermeasure against some weightlessness-induced dysfunctions. Our objective was to study whether the combination of low-magnitude whole body vibration with a resistive exercise can prevent the cardiovascular deconditioning induced by a nonstrict 60-day head-down bed rest (Earth Star International Bed Rest Experiment Project). Fourteen healthy men participated in this study. We recorded electrocardiograms and blood pressure waves by means of a noninvasive beat-by-beat measurement system (Cardiospace, integrated by Centre National d'Etudes Spatiales and Astronaut Center of China) during an orthostatic test (20 min of 75-degree head-up tilt test) before and immediately after bed rest. We estimated heart rate, blood pressure, cardiac output, stroke volume, total peripheral resistance, baroreflex sensitivity, and heart rate variability. Low-magnitude whole body vibration with resistive exercise prevented an increase of the sympathetic index (reflecting the sympathovagal balance of cardiac autonomic control) and limited the decrease of the spontaneous baroreflex sensitivity induced by 60 days of head-down bed rest. However, this countermeasure had very little effect on cardiac hemodynamics and did not improve the orthostatic tolerance. This combined countermeasure did not efficiently prevent orthostatic intolerance but prevents changes in the autonomic nervous system associated with cardiovascular deconditioning. The underlying mechanisms remain hypothetical but might involve cutaneous and muscular mechanoreceptors. autonomic nervous system; cardiovascular deconditioning; baroreflex; hemodynamic; head-up tilt test DAILY GRAVITATIONAL STRESS is necessary to maintain the cardiovascular system in a healthy state. Orthostatic challenge induces cardiac, hormonal, autonomic, macrocirculatory, and microcirculatory responses. A chronic decrease in the gravitational stress (i.e., bed rest or a weightlessness environment) impairs the cardiovascular system with a deconditioning syndrome leading to orthostatic intolerance (9). Several countermeasures were developed and tested against this orthostatic intolerance. Although aerobic exercise (24) and lower-body negative pressure (23) appear to be beneficial against orthostatic intolerance (however, not fully prevented), resistive exercise alone showed only slight effects or even no effects (3). Whole body vibration has been proposed as a countermeasure to prevent muscle and bone deconditioning induced by bed rest and an environment of weightlessness (2). A recent study (41) compared the effects of whole body vibration associated with resistive exercise versus resistive exercise alone on the vascular changes induced by 60-day bed rest. I...

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“…HU rats demonstrate many cardiovascular adaptations characteristic of cardiovascular deconditioning in humans, including a reduced exercise capacity (17, 39), orthostatic hypotension (29, 55), and a diminished capacity to elevate PVR (31, 57). This diminished ability to elevate PVR has been shown to be related to reductions in vasoconstrictor responsiveness of a number of conduit arterial segments (14,16,40,41,43,59) and skeletal muscle arterioles (13) from HU rats. However, because ϳ20% of the increase in PVR during orthostasis normally occurs as a result of vasoconstriction in splanchnic organs (42), a diminished constrictor response within the splanchnic vasculature could potentially be an underlying mechanism for orthostatic hypotension.…”

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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Vasoconstrictor properties of rat aorta are diminished by hindlimb unweighting

Cited by 77 publications

References 13 publications

Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest

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

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Vasoconstrictor properties of rat aorta are diminished by hindlimb unweighting

Cited by 77 publications

References 13 publications

Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Contractile Responses of the Basilar Artery Isolated from Rabbits Exposed to 8-Day Head-Down Tilt.

Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest

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