线粒体Cx43参与Heptanol保护兔心肌缺血/再灌注损伤

Cx43 in mitochondria participates in the protection for heptanol preconditioning on myocardial ischemia/reperfusion injury of rabbits

目的探讨线粒体Cx43和线粒体ATP敏感性钾通道(mitoKA+TP)在Heptanol保护兔心肌缺血/再灌注损伤的作用。方法兔80只,建立心肌缺血/再灌注模型,随机分5组,每组16只:假手术组(sham组)、缺血/再灌注组(IR组)、缺血预处理组(IP组)、Heptanol预处理(HT组)和5-羟葵酸加heptanol预处理组(HT+5-HD组)。测定血浆磷酸肌酸激酶同工酶(CK-MB),肌钙蛋白(cTnI)含量以及心肌梗死面积,采用电子显微镜(电镜)观测心肌线粒体结构变化,应用Westernblot检测线粒体Cx43蛋白含量。结果再灌注4h末血浆CK-MB与cTnI活性及心肌梗死面积,IP组和HT组明显低于IR组和HT+5-HD组(P<0.01)。电镜检测线粒体发现,与sham组比较,其他各组均损伤明显(P<0.01);与IR组比较,HT组、IP组(P<0.01)和HT+5-HD组(P<0.05)明显减轻;与HT+5-HD组比较,HT组和IP组损伤明显减轻(P<0.01)。Western blot检测线粒体Cx43蛋白发现,与sham组比较,HT+5-HD组和IR组线粒体Cx43蛋白明显下降(P<0.01);与IR组比较,HT组、IP组(P<0.01)和HT+5-HD组(P<0.05)心肌线粒体Cx43明显升高;与HT+5-HD组比较,HT组和IP组心肌线粒体Cx43升高(P<0.01)。结论线粒体Cx43可能参与Hep-tanol预处理的心肌保护作用,其机制可能与mitoKA+TP有关。

Aim To investigate the roles of Cx43 in mitochondria and mitochondrial ATP sensitive potassium channe1（mitoKATP^＋）participating in the protection for heptanol preconditioning on myocardial ischemia/reperfusion injury of rabbits.Methods In anesthetized open-chest rabbits,the left anterior descending artery（LAD）was occluded for 30 min and reperfused for 4 hrs.All rabbits were randomly divided into five groups（n=16 in each group）：sham operation group（Group Sham）,ischemic reperfusion group（Group IR）,ischemic preconditioning group（Group IP）,heptanol preconditioning group（Group HT）and 5-HD plus heptanol preconditioning group（Group HT＋5-HD）,All rabbits in the five groups were killed 4h after reperfusion.Myocardial infarct size was determined at the end of the experiment.The heart rate and the mean arterial pressure（MAP）were recorded and plasma CK-MB and cTnI activity were measured at baseline,the end of ischemia,and after 2 hrs and 4 hrs of reperfusion respectively.Mitochondria was isolated with different centrifugations.Ultrastructural changes of mitochondria were observed under electron microscope.The content of the mitochondria Cx43 was detected with Western blot.Results The plasma CK-MB,cTnI activity and myocardial infarct size were significantly reduced in IP（18.97±2.8）% and HT（19.97±3.8）% groups as compared to IR groups （35.67±5.8）%,（P〈0.01）.Compared to group IR,the damage of mitochondria in group IP and group HT were milder（P〈0.01）.No significant difference was found between Group IP and Group HT.Compared to sham group,the mitochondria Cx43 expression was distinctly decreased in group IR and group HT＋5-HD（P〈0.01）and no significant difference was found between Group IP and Group HT.Conclusions Heptanol preconditioning can protect the heart from I/R injury by improving mitochondrial ultrastructure and by attenuating the decrease of mitochondria Cx43 expression induced by I/R.The mitochondrial Cx43 expression may be concerned with depending on mito KATP^＋.