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

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5 min再灌注10 min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45 min再灌注60 min;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IP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lP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.

Role of mitochondrial KATP channels during ischemic preconditioning against liver ischemia/reperfosion injury in rats with cirrhosis

Objective To investigate whether the mitochondrial ATP-sensitive potassium(mi-toKATP) channels be concerned with the protection of ischemic preconditioning(IP)on liver ischemia/reperfusion(I/R)iniury in rats with cirrhosis.Methods Five groups of SD rats with liver cirrhosis(n=8 each)were pretreated with:5 min period of liver ischemia(IP group),IP plus 5-HD,a selective mitoKATP channels inhibitor 5-hydroxydecanoate(IP+5-HD group),DE,a selective mitoKATP chan-nels opener(DE group),DE plus 5-HD(DE+5-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 SLIbiected 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-pies were obtained to determine the biochemistry and pathology of the liver.Results The indexes of ATPase and the Iiver 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 lP+5-HD group(P>0.05).Conclusion The pro-tection of IP on liver I/R injury in rats with cirrhosis is correlated with the opening of mitoKATP chan-nels,possibly due to inhibited activity of ATPase.It can decrease the decompsiton of ATP,induce a-gainst oxidizing injury.improve liver microcirculation and reduce degree of hepatic tissue edema.DE can mimic the protection of IP.