Effects of spaceflight and ground recovery on mesenteric artery and vein constrictor properties in mice

Abstract

Following exposure to microgravity, there is a reduced ability of astronauts to augment peripheral vascular resistance, often resulting in orthostatic hypotension. The purpose of this study was to test the hypothesis that mesenteric arteries and veins will exhibit diminished vasoconstrictor responses after spaceflight. Mesenteric arteries and veins from female mice flown on the Space Transportation System (STS)-131 (n=11), STS-133 (n=6), and STS-135 (n=3) shuttle missions and respective ground-based control mice (n=30) were isolated for in vitro experimentation. Vasoconstrictor responses were evoked in arteries via norepinephrine (NE), potassium chloride (KCl), and caffeine, and in veins through NE across a range of intraluminal pressures (2-12 cmH(2)O). Vasoconstriction to NE was also determined in mesenteric arteries at 1, 5, and 7 d postlanding. In arteries, maximal constriction to NE, KCl, and caffeine were reduced immediately following spaceflight and 1 d postflight. Spaceflight also reduced arterial ryanodine receptor-3 mRNA levels. In mesenteric veins, there was diminished constriction to NE after flight. The results indicate that the impaired vasoconstriction following spaceflight occurs through the ryanodine receptor-mediated intracellular Ca(2+) release mechanism. Such vascular changes in astronauts could compromise the maintenance of arterial pressure during orthostatic stress.

Up-regulation of ryanodine receptor expression increases the calcium-induced calcium release and spontaneous calcium signals in cerebral arteries from hindlimb unloaded rats

“…Therefore, the aim of the present study was to test the effect of an 8-day HU on the Ca 2+ signaling toolkit of the VSMC in MCA from HU rats. Our results strongly suggest that the level of RyR expression plays a crucial role in the adaptation of VSMC from animals exposed to gravity modulation [4,12].…”

“…In the same time a decrease of RyR2 expression was found in mesenteric arteries and veins [4]. In these cases, the modification of the Ca 2+ signal only depended on the decreases in RyR1/2 expressions (without modification in VDCC-induced signals) and this was correlated with a decrease of contraction and the suspected decrease of blood loading induced by HU or μG.…”

Chronic skeletal unloading of the rat femur: Mechanisms and functional consequences of vascular remodeling

“…During the last 15-min period, the vasodilator sodium nitroprusside (10 −4 M) was added to the vessel chamber to ensure complete relaxation of the vascular smooth muscle. Maximal intraluminal diameter and medial wall thickness were first determined at the end of this second 15-min incubation using videomicroscopic techniques [29–31]. Maximal intraluminal diameter and medial wall thickness were taken as the mean of three separate measurements from positions randomly selected along the PNA length.…”

Simulated microgravity induces an inflammatory response in the common carotid artery of rats

“…of the upper body region, whereas there are atrophic adaptations and reduced contractile responsiveness in arteries of the lower body region (Tuday et al 2007;Lin et al 2009;Zhang et al 2012;Behnke et al 2013;Taylor et al 2013). For the large and elastic conduit arteries, it is reported that simulated microgravity induced an increase in blood pressure and flow in the common carotid artery of rats (Zhang 2013).…”

“…Studies of astronauts have indicated that altered autoregulation of cerebral vasculature and the inability to adequately elevate peripheral vascular resistance may be the fundamental causes for the occurrence of orthostatic intolerance after spaceflight (Blaber et al 2011;Behnke et al 2013;Taylor et al 2013). In the past few decades, ground-based animal studies using a tail-suspended hindlimb unweighted (HU) rat model have revealed that simulated-microgravity-induced arterial remodeling is different for large elastic arteries, medium-and small-sized arteries, and arterioles in different anatomic regions (Zhang 2001(Zhang , 2013.…”