Structural and functional remodeling of skeletal muscle  microvasculature is induced by simulated microgravity

Delp, Michael D.; Colleran, Patrick N.; Wilkerson, M. Keith; McCurdy, Matthew R.; Muller‐Delp, Judy M.

doi:10.1152/ajpheart.2000.278.6.h1866

Cited by 137 publications

(187 citation statements)

References 30 publications

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“…Specifically, absolute vascular conductance was decreased to a greater extent in muscles composed of proportionally more FOG and SO fibres than in their FG-containing counterparts. Consistent with our results, others Delp et al 2000) have shown previously that isolated arterioles from slow twitch muscle (i.e. the soleus) demonstrate a more potent vasodilatation in response to dilators acting through the vascular endotheliuni when compared to the response in isolated arterioles from fast twitch muscle (i.e.…”

Section: Discussionsupporting

confidence: 93%

Effects of nitric oxide synthase inhibition on vascular conductance during high speed treadmill exercise in rats

Musch

McAllister

Symons

et al. 2001

Experimental Physiology

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To determine the functional role of nitric oxide (NO) in regulating vascular conductance during high intensity dynamic exercise in skeletal muscles composed of all major fibre types, female Wistar rats (277 f 4 g; II = 7) were run on a motor-driven treadmill at a speed and gradient (60 m min-', 10% gradient) established to yield maximal oxygen uptake ( T & , , , , , ) .Vascular conductance (ml min-' (100 g)-' mmHg-'), defined as blood flow normalised to mean arterial pressure (MAP), was determined using radiolabelled microspheres during exercise before and after N O synthase (NOS) inhibition with NG-nitro-L-arginine methyl ester (L-NAME; 10 mg kg-', LA.). The administration of L-NAME increased MAP from pre-L-NAME baseline values, demonstrating that NOS activity is reduced. The administration of L-NAME also reduced vascular conductance in 20 of the 28 individual hindlimb muscles or muscle parts examined during high speed treadmill exercise. These reductions in vascular conductance correlated linearly with the estimated sum of the percentage of slow twitch oxidative (SO) and fast twitch oxidative glycolytic (FOG) types of fibres in each muscle (Aconductance = -O.O082(%SO + %FOG) -0.0105; r = 0.66; P < 0.001). However, if the reduction in vascular conductance found in the individual hindquarter muscles or muscle parts was expressed as a percentage decrease from the pre-L-NAME value (%A = (pre-L-NAME conductance -post-L-NAME conductance)/pre-L-NAME conductance x loo), then the reduction in vascular conductance was similar in all muscles examined (average %A = -23 k 2 % ) .These results suggest that N O contributes substantially to the regulation of vascular conductance within and among muscles of the rat hindquarter during high intensity exercise. When expressed in absolute terms, the results suggest that the contribution of NO to the regulation of vascular conductance during high intensity exercise is greater in muscles that possess a high oxidative capacity. In contrast, if results are expressed in relative terms, then the contribution of N O to the regulation of vascular conductance during high intensity exercise is similar across the different locomotor muscles located in the rat hindlimb and independent of the fibre type composition. Experimental Physiology (2001) 86.6,749-757.

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Section: Discussionsupporting

confidence: 93%

Effects of nitric oxide synthase inhibition on vascular conductance during high speed treadmill exercise in rats

Musch

McAllister

Symons

et al. 2001

Experimental Physiology

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“…38 In the present study, we observed a decrease in systolic and MAP in the 6 weeks after SCI. In a previous deconditioning study in hindlimb unloaded rats, Delp at al 4 observed that reductions in transmural pressure induced atrophy of smooth muscle cells with no changes in vessel diameter. In addition, vascular adaptations to deconditioning with no changes in blood pressure were reported previously after 4 weeks of lower-limb suspension.…”

Section: Leg Volume and Blood Pressurementioning

confidence: 97%

“…Adaptations in vascular tone occur within days, whereas chronic and structural changes of the vessel wall are completed within 2 to 3 weeks. [3][4][5] In humans with longstanding SCI, extensive adaptations occur in the peripheral circulation such as a 30% decrease in diameter, a reduction in blood flow, and an almost doubling of stress levels in the femoral artery. 1,[6][7][8] Results on vascular changes derived from other models of deconditioning like bedrest studies [9][10][11] conflict with some studies showing a decrease in leg blood flow and others showing no changes after a period of bedrest varying from 10 to 41 days.…”

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confidence: 99%

Rapid and Extensive Arterial Adaptations After Spinal Cord Injury

Groot¹,

Bleeker²,

Kuppevelt³

et al. 2006

Archives of Physical Medicine and Rehabilitation

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Objective: To assess the time course of adaptations in leg vascular dimension and function within the first 6 weeks after a spinal cord injury (SCI).Design: Longitudinal study design. Setting: University medical center and rehabilitation clinic. Participants: Six men were studied serially at 1, 2, 3, 4, and 6 weeks after SCI.Interventions: Not applicable. Main Outcome Measures: Diameter, blood flow, and shear rate levels of the common femoral artery (CFA), superficial femoral artery (SFA), brachial artery, and carotid artery were measured with echo Doppler ultrasound (diameter, blood flow, shear rate). Endothelial function in the SFA was measured with flow-mediated dilation (FMD). In addition, leg volume and blood pressure measurements were performed.Results: Femoral artery diameter (CFA, 25%; SFA, 16%; PϽ.01) and leg volume (22%, PϽ.01) decreased simultaneously, and these reductions were largely accomplished within 3 weeks postinjury. Significant increases were observed for basal shear rate levels (64% increase at week 3; 117% increase at week 6; PϽ.01), absolute FMD responses (8% increase at week 3, 23% increase at week 6; PϽ.05) and relative FMD responses (26% increase at week 3, 44% increase at week 6; PϽ.001).Conclusions: Our findings show a rapid onset of adaptations in arterial dimension and function to extreme inactivity in humans. Vascular adaptations include extensive reductions in femoral diameter and leg volume, as well as increased basal shear rate levels and FMD responses, which all appear to be largely accomplished within 3 weeks after an SCI.

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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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Structural and functional remodeling of skeletal muscle microvasculature is induced by simulated microgravity

Cited by 137 publications

References 30 publications

Effects of nitric oxide synthase inhibition on vascular conductance during high speed treadmill exercise in rats

Effects of nitric oxide synthase inhibition on vascular conductance during high speed treadmill exercise in rats

Rapid and Extensive Arterial Adaptations After Spinal Cord Injury

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

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