缝隙连接蛋白43在七氟醚后处理保护大鼠离体心肌缺血再灌注中的作用

目的探讨缝隙连接蛋白(connexin,Cx)43在七氟醚后处理保护大鼠离体心肌缺血再灌注中的作用。方法健康成年雄性SD大鼠40只,体质量200～250 g,采用随机数字表法将其分为4组(n=10):缺血再灌注组(IR组)、七氟醚后处理组(S组)、七氟醚混合5-羟基葵酸钠(5-HD)组(SH组)及5-HD组(H组)。采用Langendorff装置进行离体心脏灌注。各组均在阻断左冠状动脉(LAD)前维持灌注10 min,然后阻断LAD血流30 min后开放,再灌注120 min,其中S、SH及H组分别于LAD开放后使用3%七氟醚预饱和的K-H液、3%预饱和的七氟醚预充饱和的K-H加5-HD(100μmol/L)及加入5-HD(100μmol/L)的K-H液灌注15 min,然后使用普通K-H液继续灌注105 min。分别于阻断LAD前即刻(T0),开放LAD即刻(T1),开放LAD后15 min(T2),开放LAD后135 min(T3)时记录HR、左心室收缩压(LVSP)、左心室舒张压(LVDP)、左心室最大上升及下降速率(±dp/dtmax)。再灌注结束后,取左心室TTC染色测定心肌梗死面积,采用免疫组化染色观测Cx43蛋白表达情况,采用Western blot法检测Cx43蛋白及磷酸化Cx43(p-Cx43)蛋白含量。结果与IR组比较,S组的HR、LVSP、±dp/dtmax较高,LVDP降低,心肌梗死面积小,Cx43蛋白及p-Cx43蛋白含量增加,有统计学意义(P<0.05)。IR组与SH组及H组之间相比HR、LVSP、±dp/dtmax、LVDP、心肌梗死面积、Cx43蛋白和p-Cx43蛋白差异无显著性(P>0.05)。结论七氟醚后处理减轻离体大鼠心肌IR损伤的作用可能与其开放线粒体敏感钾通道从而促进Cx43蛋白表达及其磷酸化有关。

Role of connexin 43 in protecting rat myocardium against ischemia/reperfusion injury in vitro at sevoflurane post-conditioning

Objective To study the role of connexin43(Cx43) in protecting rat myocardium against ischemia/reperfusion(I/R) injury in vitro at sevoflurane post-conditioning.Methods Forty healthy adult male SD rats,weighing 200-250 g,were randomly divided into I/R group,sevoflurane post-conditioning group(group S),combined sevoflurane and 5-HD group(group SH),and 5-HD group(group H),10 in each group.In vitro heart was perfused with a Langendoff device for 10 min before the left coronary artery was occluded.The left coronary artery was reperfused after its blood flow was occluded for 30 min followed by 120 min-reperfusion.HR,LVSP,LVDP,and dp/dt_max were recorded at occlusion of left coronary artery(T0),intermediate reperfusion(T1),15 min-reperfusion(T2) and 135 min-reperfusion(T3),respectively.After reperfusion,myocardial infarct size was measured with TTC staining and expression level of Cx43 and its phosporylation protein p-Cx43 was measured with immunohistochemistry staining and Western blotting,respectively.Results The HR,LVSP and dp/dt_max were higher,the LVDP was lower,the myocardial infarct size was smaller,and the expression level of Cx43 and its p-Cx43 was higher in group S than in I/R group(P<0.05).However,no difference was found in the above parameters among I/R group,group SH and group H(P>0.05).Conclusion The role of Cx43 in protecting rat myocardium against I/R injury in vitro at sevoflurane post-conditioning may be related with the open mito-KATP,and thus promote expression of Cx43 and its p-Cx43.