缺血预处理对大鼠肝脏缺血/再灌注损伤的延迟保护作用及机制

目的 研究缺血预处理(IPC)对大鼠肝脏缺血/再灌注损伤的延迟保护作用,并探讨线柱体ATP敏感性钾通道(mitoKATP通道)在这种保护机制中的作用. 方法 SD大鼠随机分为5组(每组8只).IPC组以肝缺血5 min作预处理;DE组以静脉注射mitoKATP通道选择性开放剂二氮嗪(DE)作为预处理;IPC+5-HD组是在IPC组基础上再予静注mitoKATP通道特异性阻滞剂5-hydroxydecanoate(5-HD)进行预处理;对照组(C组)仅以静注等量生理盐水作为预处理;上述4组均在预处理24 h后行肝缺血1 h再灌注3 h,缺血方式均为70%肝脏热缺血.假手术组(S组)仅行两次开腹手术,不作其它处理.完成预定实验操作后取血用于血清谷丙转氨酶(ALT)与乳酸脱氢酶(LDH)检测,切取肝组织用于测定超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、湿重/干重(W/D)及观察显微及超微结构变化. 结果 C组ALT,LDH,MDA及W/D值明显高于S组(P<0.01),而SOD活性明显低于S组(P<0.01),肝脏的显微及超微结构损伤明显;IPC组与DE组的各项肝损伤指标均明显好于C组(P<0.05及P<0.01);IPC+5-HD组的肝损伤指标均差于IPC组(P<0.05及P<0.01). 结论 缺血预处理对正常大鼠肝脏I/R损伤具有延迟保护作用,肝细胞mitoKATP通道的开放在其中发挥了重要作用,作用途径可能与诱导肝脏SOD活性增加,改善肝组织微循环,减轻肝脏水肿有关.

Experimental study on the action and mechanism of delayed protection of ischemic preconditioning on liver ischemia/reperfusion injury in rats

Objective To investigate the likelihood of ischemic preconditioning (IPC) inducing delayed protection against liver ischemia/reperfusion injury in rats, and determine whether this protection works through mitochondrial ATP-sensitive potassium (mitoKATP) channels. Methods Four groups of SD rats (n=8 each) were pretreated with: 5-min period of liver ischemia (IPC group), diazoxide(DE group), IPC plus 5-hydroxydecanoate (IPC 5-HD group) and saline(control group). Twenty-four hours later, the pretreated rats were subjected to 60 min sustained liver ischemia followed by 180 min reperfusion. All rats were subjected to 70% liver ischemia. An additional the fifth group of rats was set(sham group), in which only anesthesia and laparotomy was performed twice. Finally, blood and liver samples were obtained to determine the biochemistry and pathology of the liver. Results The activities of alanine aminotransferase and lactic dehydrogenase, content of malondialdehyde and level of W/D were higher (P< 0.01) and the activities of superoxide dismutase were lower (P< 0.01) in C group than those in S group. There were also severe morphologic damages in C group. All of the liver injury indexes in IPC group and DE group were better than those in C group (P< 0.05 or P< 0.01). IPC 5-HD group had the adverse change, contrasted with IPC group (P< 0.05 or P<0.01). Conclusion IPC can lessen hepatic ischemia/ reperfusion injury through delayed protection due to increased activity of SOD and improves liver microcir-culation, which is correlated with the opening of mitoKATP channels.