Alteration of vasoreactivity of mesenteric arteries in rats after two-week simulated weightlessness

To investigate the effects of simulated weightlessness on vasoreactivity of mesenteric arteries, rats were tail-suspended for two weeks, and vasoreactivity were studied in vitro using isolated mesenteric arterial ring. The results showed that maximal contractile responses to KCl (10-80 mmol/L) and phenylephrine (PE, 10(-10)-10(-4) mol/L) were attenuated in arterial rings isolated from tail-suspended rats. After constriction caused by 10(-7) mol/L PE, maximal dilatory responses induced by sodium nitroprusside (SNP, 10(-10)-10(-4) mol/L) were not different between tail-suspended and control groups. These data indicated that contractile ability of mesenteric artery was diminished by tail-suspension, whereas the dilatory capacity of arterial smooth muscle was not altered.