尾部悬吊及恢复过程中大鼠动脉血管收缩反应的变化

目的 探讨模拟失重下动脉收缩反应变化的时程特征及其可逆性。方法 采用尾部悬吊大鼠模型模拟失重，利用离休动脉环测定血管收缩反应的变化。结果 尾部悬吊２ｗｋ后，大鼠的腹主动脉、肠系膜动脉和股动脉收缩反应明显降低，而颈总动脉无明显改变；悬吊４ｗｋ后，肠系膜动脉和股动脉的收缩反应与悬吊２ｗｋ相比有进一步的降低；悬吊８ｗｋ大鼠的动脉血管收缩反应性与悬吊４ｗｋ相比无明显差异；４ｗｋ尾部悬吊大鼠解除悬吊后５ｗｋ

Alterations of Arterial Vasoconstrictor Responsiveness in Rats during and after Tail-Suspension

Objective To characterize the time course of alterations in vasoconstrictor properties of arteries during simulated weightlessness, and to examine whether these alterations are reversible. Method The tailsuspended rat model was used to simulate weightlessness, and the alterations in vasoconstrictor response were examined in vitro using isolated arterial rings. Result Compared with that of controls, contractile tension evoked by KCl and phenylephrine (PE) were lower in abdominal aortic, mesenteric and femoral arterial rings from 2 wk tailsuspended rats ( P <0.05); after 4 wk tailsuspension, the responses of mesenteric and femoral arterial rings to KCl or PE were further decreased ( P<0.05); but contraction responses of arterial rings from 8 wk tailsuspended rats were similar to that of 4 wk simulated microgravity rats. The reversibility of altered arterial vasoreactivity after 4 wk tailsuspension was observed for 5 wk.Vasoreactivity of abdominal aortic rings was recovered after first week of recovery, but it took five weeks that altered vasoreactivity of mesenteric and femoral artery got back to normal. Conclusion The alterations in constrictor properties of arteries are dependent on both the duration of tailsuspension and the position of artery, the diminished vasoconstrictor properties appear to reach a new steady state after 4 wk tailsuspension, and the changes are reversible.