线粒体ATP敏感性钾通道在缺血预处理保护硬化肝脏中的作用

Role of mitochondrial KATe channels during ischemic preconditioning against liver ischemia/reperfusioninjury in rats with cirrhosis

目的研究缺血预处理（IP）对肝硬化大鼠肝脏缺血／再灌注（I／R）损伤的保护作用，探讨线粒体ATP敏感性钾通道（mitoKATP通道）在这种保护机制中的作用。方法复制雄性肝硬化SD大鼠，随机分为6组（每组8只）。IP组以肝缺血5min再灌注10min作预处理；IP＋5-HD组是在IP组基础上，使用微量注射泵经大鼠门静脉注射mitoKATP通道特异性阻滞剂5-HD进行预处理；DE组以静脉注射mitoKATP通道选择性开放剂DE作为预处理；DE＋5-HD组是在DE组基础上再予静脉注射5-HD进行预处理；对照组（C组）以静脉注射等量生理盐水作为预处理；上述5组均在预处理后行肝缺血45min再灌注60min；缺血方式为70％肝脏热缺血。假手术组（S组）仅行开腹，不作任何其它处理。完成预定实验操作后分别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ATP酶活力、超氧化物岐化酶（SOD）活性、丙二醛（MDA）含量、湿重／干重（W／D）的测定及观察显微、超微结构变化。结果C组ATP酶活性与肝损伤指标ALT与LDH活性、MDA含量与W／D比值均明显高于S组（P％0．01），肝脏在光镜与电镜下的显微与超微结构损伤明显；IP组与DE组的各项肝组织损伤指标均明显好于C组，ATP酶活性低于C组（P〈0．05，P〈0．01），而IP＋5-HD组、DE＋5-HD组的肝损伤指标分别差于IP组、DE组，ATP酶活性高于1P组、DE组（P〈0．05，P〈0．01）；在SOD活性方面，C组明显低于S组（P〈0．01），IP组低于S组，高于C组（P〈0．01），DE组与C组相比无差异，IP＋5-HD组、DE＋5-HD组SOD活性分别与IP组、DE组相比无差异（P〉0．05）。结论mitoKATP通道参与IP抗肝硬化大鼠肝I／R损伤的保护效应，其作用可能与下调肝组织ATP酶活性，减少ATP大量分解，改善肝能量代谢，增加能量储备；提高肝脏的抗氧化能力；改善肝组织微循环，减轻肝脏水肿有关。

Objective To investigate whether the mitochondrial ATP-sensitive potassium （mitoKATP） channels be concerned with the protection of ischemic preconditioning （IP） on liver ischemia/ reperfusion（I/R） injury in rats with cirrhosis. Methods Five groups of SD rats with liver cirrhosis （n =8 each） were pretreated with.. 5min period of liver ischemia （IP group）, IP plus 5-HD, a selective mitoKATe channels inhibitor 5-hydroxydecanoate （IP＋ 5-HD group）, DE, a selective mitoKATP channels opener （DE group）, DE plus 5-HD （DE-k5-HD group）, and with saline （control group）. The pretreated rats were subjected to 45 min sustained liver ischemia followed by 60 min reperfusion. All rats were subjected to 70% liver warm ischemia. In addition, the sixth group was established （sham group, n=8）, in which only anesthesia and laparotomy was performed. Finally, blood and liver sam- ples were obtained to determine the biochemistry and pathology of the liver. Results The indexes of ATPase and the liver injury indexes including ALT, LDH, MDA and W/D were higher in C group than in S group （P〈0. 01）. There were also severe histological and ultra structure damages in C group. The activity of ATPase was lower and all the injury indexes in IP group and DE group were better than those in C group （P〈0.05 or P〈0.01）. IP＋5-HD group and DE＋5-HD group had the adverse changes as compared with DE group （P〈0.05 or P〈0.01）. The activity of SOD in IP group was higher than that in C group （P〈0.01）, whereas there was no significant difference between DE and C group, DE and DE＋5-HD group, IP and IP＋5-HD group （P〉0.05）. Conclusion The protection of IP on liver I/R injury in rats with cirrhosis is correlated with the opening of mitoKATP channels, possibly due to inhibited activity of ATPase. It can decrease the decompsiton of ATP, induce against oxidizing injury, improve liver microcirculation and reduce degree of hepatic tissue edema. DE can mimic the protection of IP.