脑缺血再灌注后血栓形成与血浆纤维蛋白原水平的变化

Changes of Thrombosis Plasma Fibrinogen During Cerebral Ischemia Reperfusion

目的 :在动物活体模型上 ,连续观察脑缺血 /再灌注时脑软膜微血管内血栓形成的过程并测量缺血 /再灌注不同时期血浆纤维蛋白原的变化。方法 :用夹闭沙土鼠双侧颈总动脉的方法复制脑缺血再灌注模型。颈动脉注入 0 .0 67%异硫氢酸荧光黄 (FITC) 0 .2ml后 ,在荧光显微镜下观察脑软膜微血管内血栓形成的过程 ,并在缺血 15min、30min、再灌注 30min、1h、6h时采血 ,用凝血酶凝固法测量血浆纤维蛋白原。结果 :单纯缺血期血流速度明显减慢 ,细动脉、细静脉管径缩小 ,有部分毛细血管内血流停滞。再灌注后 ,血流速度加快 ,随再灌时间的延长 ,白细胞粘附、贴壁明显增多 ,血管内皮增厚 ,纤维蛋白丝网络血细胞及血小板 ,呈絮状团块附着在血管内壁上 ,逐渐形成壁栓 ,阻碍血细胞的流过。缺血期和再灌注后血浆纤维蛋白原水平均高于正常对照组 ,以缺血 30min和再灌 1h时增高最为明显 (P <0 .0 1)。再灌 6h时又明显降低 ,与单纯缺血 30min组比较有显著性差异 (P <0 .0 1)。结论 :再灌注后快速恢复的血流加重了内皮细胞的损伤 ,白细胞、血小板粘附 ,导致血栓形成 。

Objective: To observe the formation of thrombus in vivo during cerebral ischemia/reperfusion and to investigate the role of plasma fibrinogen in above process.Method: Mongolian gerbil were used for cerebral ischemia/reperfusion by cramping the common carotid artery.Thrombosis observed under Fluorescent microscope after injection of fluorescein isothioyanate(FITC).The plasma fibrinogen were measured after 15 min,20 min of ischemia and 30 min,1 h,6 h of reperfusion.Results: Microcirculatory observation showed the decreasing of blood velocity and narrowing of venules and arterioles and partially closing of the capillary during the ischemic period.When the clamp was released,the blood reperfused to the ischemic vessel with more rapid flow.The leukocytes was observed adhering on the surface of endothelium,platelets aggregating and the fibrin depositing on the microvessels in a time dependent manner during reperfusion.The filamentous fibrin neted the platelets and leukocytes to adhere to the vessel wall which formed microthrombuses to obstruct the blood flow.The plasma fibrinogen in ischemia/reperfusion.group were higher than that of control group.The highest level were in group of 15 min ischemia and 1 h reperfusion( P<0.01 ).The levels of plasma fibrinogen in group of 6 h reperfusion were significantly decreased.Conclusion: These results indicated that the ischemia/reperfusion cause endothelia damage followed by leukocytes and platelets adhesion and formation fibrin rich thrombuses.The fibrin appears to play an important role in the thrombosis.