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目的探讨模拟失重所致动脉收缩反应性降低的机理。方法大鼠通过尾部悬吊方法模拟失重，尾部悬吊４周后，采用机械法去除血管内皮，利用离体去内皮股动脉环测定股动脉对血管活性物质的反应。使用台式自动平衡记录仪记录肌张力变化并与对照组对比。结果模拟失重大鼠去内皮股动脉环对多种血管活性物质的收缩反应均明显降低，主要表现为：①受体介导的动脉收缩反应，如苯肾上腺素（１０－９～１０－４Ｍ）、内皮素－１（１０－１０～１０－７Ｍ）及血管加压素（１０－１２～１０－７Ｍ）诱发的收缩反应，在４周模拟失重大鼠明显低于对照大鼠（Ｐ＜０．０５）；②非受体介导的收缩反应，如氯化钾（１０～９０ｍＭ）导致的收缩反应在尾部悬吊组也明显低于对照组（Ｐ＜０．０１）；③模拟失重大鼠去内皮股动脉环对钙离子（１０－５～５×１０－３Ｍ）及１０－６Ｍ钙离子载体（ｉｏｎｏｐｈｏｒｅ）Ａ２３１８７所激发的收缩反应亦明显弱于对照大鼠（Ｐ＜０．０５）；④动脉对上述物质反应的敏感性（ＥＣ５０）在模拟失重大鼠与对照大鼠间无明显差别。结论虽然不能完全排除钙离子通道改变或受体活化后信号转录系统改变的可能，但结果足以说明这些可能在造成后身动脉收缩反应变化中的作用不重要。而模拟失重下动?
Objective To explore the mechanism of reduced arterial contractile response induced by simulated weightlessness. Methods The rats were subjected to tail suspension to simulate the weightlessness. After the tail was suspended for 4 weeks, the vascular endothelium was removed by mechanical method. The response of the femoral artery to vasoactive substances was measured by extirpation of the endothelial femoral artery rings. The changes of muscle tone were recorded using a desktop autobalance recorder and compared with the control group. Results The contractile responses of endothelium-free femoral artery rings to simulated vasoactive substances in simulated weightless rats were significantly decreased. The main manifestations were: (1) receptor-mediated arterial contractions, such as phenylephrine (10-9-10-4M) , Endothelin-1 (10-10 ~ 10-7M) and vasopressin (10-12 ~ 10-7M) induced contractile response in simulated weightless rats at 4 weeks were significantly lower than those in control rats (P <0, P < .05). ② Non-receptor-mediated contractile responses such as potassium chloride (10-90 mM) caused a significant decrease in contractile response in the tail suspension group compared with the control group (P <0.01). ③ Simulated weight loss The contractile responses induced by calcium ion (10-5 ~ 5 × 10-3M) and ionophore A23187 in rat aortic endothelium were also significantly weaker than those in control rats (P <0.05) ; ④ The arterial sensitivity to the above reaction (EC50) showed no significant difference between simulated weightless rats and control rats. Conclusions Although the possibility of alterations in calcium channels or signal transduction systems after receptor activation can not be completely ruled out, the results are sufficient to demonstrate that these effects, which may contribute to the changes in the contractile responses of the posterior arteries, are unimportant. Simulated weightlessness move?