内毒素休克时大鼠肠系膜微血管对去甲肾上腺素反应性的变化

本文应用微循环显微也视录象技术,研究内毒素休克大鼠在休克不同时期肠系膜微血管对去甲肾上腺素(NA)反应性的变化。发现局部滴用由低至高浓度NA使微血管口径呈剂量依赖性缩小,对照组在相当于休克相应时间三次观察收缩反应曲线无明显差异(P>0.05),而休克早期微血管对NA的缩血管反应明显,晚期收缩反应减弱(均P<0.01);同时,休克早期浓度—反应曲线右移,EC_(50)减小,反应阈值降低;休克晚期浓度—反应曲线左移,EC_(50)增大,反应阈值增高;但对照组三次观察无明显变化。提示内毒素休克早期微血管对NA的反应性增高,晚期反应性降低,一、二级细动脉的变化尤为显著。可能是休克早期的代偿与晚期的失代偿机理之一。

Response change of rat mesenteric microvessels to noradrenaline during endotoxic shock

The response of rat mesenteric microvessels to noradrenaline (NA) in different stages of endotoxic shock was investigated by using vital microscope with video television recorder. It was found that the diameter of the microvessels showed a dose-dependent decrease to local NA application from the low to high concentration. The constricted response curve was remained unchanged at the experimental duration. The constricted response to NA was increased significantly at early stage of shock but was decreased at late stage (both P<0.01). The NA concentration-response curve shifted to right, EC_(50) reduced, and the threshold of response decreased at early stage of shock, but the NA concentration-response curve shifted to left, EC_(50) enhanced, threshold of response increased at the late stage. No such changes were found in control group.Results suggested the response to NA was enhanced during early stage but was reduced at late stage, such changes were more significant in arteriole A_1, A_2, and may play role in compensation at early stage of shock and on decompensation at late stage.