有氧运动对低氧大鼠动脉内皮素反应敏感性的影响

目的：了解有氧运动对低氧状态下大鼠动脉血管对内皮素（ET-1）反应的影响。方法：8周大的雄性sD大鼠，随机分为4组，训练组分别进行7周每天1h的游泳训练。分离出大鼠胸动脉，检测4组动脉环中ET-1含量、eNOS蛋白表达，以及动脉环在有、无内皮情况下和有特异性抑制剂时对ET-1的反应。结果：常氧下运动后动脉上ET-1含量减少，内皮eNOS蛋白表达增加，动脉血管对ET-1的敏感性明显下降（P〈0．05），低氧下动脉环ET_1的含量增加．内皮eNOS蛋白表达减少。有氧运动后尽管其动脉环上ET-1的含量有所下降（P〈0．05），但eNOS蛋白表达的增加很有限，低于N、NE组（P〈0．05）．有氧运动对内皮性ET-1受体介导的对ET-1反应的调节作用有限。结论：有氧运动的益处在于通过增强内皮功能，调节动脉对ET-1的反应性。而低氧状态下有氧运动对经内皮性ET-1受体介导的动脉血管对ET-1反应的调节作用有限。

Effect of Aerobic Exercise on Hypoxia- Induced Aortic Sensitivity to Endothelin of Rats

Objectives: The purpose is to investigate the effect of aerobic exercise on vascular reactivity alterations to endothelin(ET-1) following prolonged exposure to hypoxic stress.Methods: 8 weeks old SD male rats were randomly assigned to N,NE,CH and CHE groups respectively.After 50 days,one-hour swimming training per day(5 days/week),the concentration of the ET-1 in thoracic aorta,expression of eNOS protein in the endothelium,the effects of ET-1 in the presence or not of the endothelium and of the specific inhibitor,had been determined in an isolated model of rat thoracic aorta.Results: Exercise training increased expression of eNOS protein,reduced the concentration of the ET-1 in thoracic aorta and the sensitivity to ET-1 in normoxic rats(P<0.05).Prolonged exposure to hypoxia induced a decrease expression of eNOS protein,a significant increase in the concentration of the ET-1 and aortic sensitivity to ET-1(P<0.05).Despite aerobic exercise training reduced the concentration of the ET-1,limit increase in expression of eNOS protein(P<0.05),it was limit to regulate the ET-1 induced vasoconstriction by the endothelial ET-1 receptors in hypoxic rats.Conclusion: It clearly suggested that part of the beneficial effect of aerobic exercise could be mediated by enhancing endothelial function associated with endothelin reactivity in aorta.However,in chronic hypoxia exposure,aerobic exercise training seemed limit to regulate the ET-1 induced vasoconstriction by the endothelial ET-1 receptors.