观察动物内耳缺血再灌注对耳蜗的影响

Effect of inner ear ischemia/reperfusion on cochlea

目的探讨内耳缺血再灌注对耳蜗的影响。方法随机将豚鼠分为5组:正常组、缺血30min组、缺血30min再灌注组、缺血60min组、缺血60min再灌注组。手术经颅底暴露小脑前下动脉(AICA),缺血组使用40%FeCl3溶液诱导AICA形成血栓;缺血再灌注组经颈外静脉给予尿激酶(UK)溶解血栓。实验中采用激光多普勒血流量仪监测耳蜗血流量(CoBF),实验前后测量豚鼠听性脑干反应(ABR)值、畸变产物耳声发射(DPOAE)值,实验后耳蜗基底膜铺片硝酸银染色,光镜观察。结果血栓组在FeCl3诱导后CoBF值下降至诱导前约30%,溶栓组在用UK后CoBF恢复到诱导前大约70%。缺血时间越长ABR阈值越高,各频率DPOAE幅值下降越明显,毛细胞破坏越严重;缺血时间相等时再灌注组ABR阈值高,DPOAE幅值下降明显,毛细胞破坏严重。外毛细胞较内毛细胞更易受影响。结论缺血/再灌注可引起耳蜗的损伤。

Objective To study the effect of inner ear ischemia/reperfusion on cochlea. Methods Guinea pigs were randomly allocated into normal group, 30min ischemia group, 30min ischemia/reperfusion group, 60min ischemia group, and 60min ischemia/ reperfusion group. Anterior inferior cerebellar artery（AICA） was exposed at surgery via the base of skull. In ischemia group, a small piece of filter paper containing 5ul FeCl3 was placed upon the AICA to induce formation of thrombus. In reperfusion group, animals were injected with urokinase （UK） through the left external jugular vein after the formation of thrombus. Blood flow in cochlea was monitored continuously with a laser Doppler flow meter. ABR and DPOAE were tested before and after each experiment. Then, surface preparation samples of basilar membrane were stained with AgNO3 and observed under a light microscope. Results After administration of FeCl3, the blood flow in cochlea was declined to 30% of the base level. In reperfusion group, the blood flow in cochlea was returned to 70% of the base level after injection of UK. The longer the ischemia was, the higher the ABR threshold was. The damage was severer to outer hair cells than to inner hair cells. Conclusion Ischemia/reperfusion can induce injury of cochlea.