缺血预处理对缺血/再灌注脑的保护及其与微循环调节功能的关系研究

Protective effect of ischemic preconditioning on rat brain with ischemia/reperfusion injury

目的 :探讨缺血预处理 (IPC)是否对缺血 /再灌注 (I/R)脑细胞具有保护效应及其与微循环调节功能间的关系。方法 :I/R与IPC组大鼠均复制脑I/R损伤模型 ,IPC组增加于I/R之前 2 4h进行的短暂脑缺血预处理。动物均开颅窗观察缺血前、缺血后、再灌后脑软膜微循环指标 ;并取脑组织作红四氮唑 (TTC)染色观察缺血损伤情况。结果 :I/R组TTC染色后大多数出现不规则的缺血损伤的淡染区 ,而IPC组明显少见。IPC组缺血及再灌之后毛细血管累计总长度、微循环血流量、微血管内血流速度之相对增加值均大于I/R组。I/R组于再灌注之后有无复流现象 ;而IPC组此时呈灌注增加的过程。结论 :IPC通过提高微循环的调节功能 ,促进毛细血管的相对性开放和血流的相对性加快 ,减轻缺血期组织血流低灌注和再灌注期无复流现象 ,从而对I/R脑产生一定保护作用。

AIM:To study whether ischemic preconditioning(IPC) has a protective effect against ischemia/reperfusion(I/R) injury in brain, and the possible relationship between IPC and the regulating function of microcirculation. METHODS: The I/R models were established both in I/R and IPC groups of Sprague-Dawley rats. Additional procedure was performed of short term cerebral ischemic preconditioning in IPC group 24 hours before I/R. Skull windows were performed through which microcirculation features were measured before ischemia, during ischemia, and reperfusion. Finally, brains were cut into slices and stained with red tetrazoline(TTC). RESULTS: Most TTC stained brains in I/R group presented irregular palely red areas which were few in IPC group. Compared with I/R group, IPC group presented relatively increase in accumulated length of capillaries, mean cerebral microcirculatory perfusion, and microcirculatory velocity in ischemic and reperfusion phase. There was no-reflow phenomenon in I/R group in reperfusion phase, which was substituted by the course of increasing reperfusion in IPC group. CONCLUSIONS:IPC could relieve the reduction of tissue perfusion during ischemia and the no-reflow phenomenon during reperfusion by improving the regulating function of microcirculation, which relatively promote the opening of capillaries and accelerating of microvascular flow, therefore protect brain from I/R injury.