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 cmH2O).