肢体缺血再灌注后微动脉对去甲肾上腺素、乙酰胆碱及硝酸甘油反应性变化

CHANGES OF THE RESPONSES OF ARTERIOLES TO NORADRENALINE, ACETYLCHOLINE AND NITROGLYCERIN AFTER LIMB ISCHEMIA REPERFUSION

目的 探讨肢体缺血再灌注后微血管痉挛的发生机制。方法 应用兔后肢止血带常温缺血模型及足背肌腱表面微循环观察法 ,观察肢体缺血 2小时及 5小时再灌注后微动脉对局部滴注血管收缩剂 [去甲肾上腺素 (10 - 6 mol/ L ) ]、内皮依赖性血管舒张剂 [乙酰胆碱 (10 - 6 mol/ L ) ]及内皮非依赖性血管舒张剂 [硝酸甘油(10 - 4 mol/ L) ]的反应性变化。结果 与缺血前比较 ,肢体缺血 2小时再灌注后 ,微动脉对上述三种血管活性物质的反应性均无显著性变化 ;缺血 5小时再灌注后 ,微动脉对去甲肾上腺素的收缩反应仍无显著性变化 ,但对乙酰胆碱及硝酸甘油的舒张反应均见减弱 ,对乙酰胆碱的反应减弱非常显著 (P<0 .0 1) ,对硝酸甘油的反应减弱显著 (P<0 .0 5 )。结论 肢体缺血 2小时再灌注后 ,微动脉内皮依赖性和非依赖性舒张机制均无显著损害 ,但缺血 5小时再灌注后则上述两种血管舒张机制均受妨碍 ,尤以内皮依赖性舒张为著 ,这可能是长时间缺血肢体再灌注后发生微血管痉挛的主要原因。

Objective To explore the mechanism of microvascular spasm after limb ischemia reperfusion.Methods The rabbit hindlimb normothermic tourniquet ischemia model was employed. The tendon on the dorsum of the foot was exposed for observation of microvessels. The responses of arterioles on tendon surface to topical application of 10 -6 mol/L noradrenaline (NE) (a vasoconstrictor), 10 -6 mol/l acetylcholine(Ach) (an endothelium dependent vasodilator) and 10 -4 mol/L nitroglycerin(NTG) (an endothelium independent vasodilator) were observed at the period of ischemia and following 30 minutes of reperfusion after 2 hours and 5 hours of ischemia by use of intravital microscopy.Results\ No significant changes in the responses of arterioles to NE, Ach and NTG were noted following 30 minutes of reperfusion after 2 hours of ischemia compared with pre ischemia. The constrictor responses of arterioles to NE were still not singificantly altered following 30 minutes of reperfusion after 5 hours of ischemia, however, the dilation responses to Ach and NTG were signficantly decreased (to Ach P<0.01; to NTG, P<0.05).Conclusion\ Reperfusion after 5 hours of ischemia significantly impairs both the endothelium dependent and endothelium independent vasodilation, meanwhile preserves constrictor responses to NE, these may contribute to the genesis of the vasospasm in ischemia reperfusion.