缝隙连接蛋白Cx43介导硫化氢后处理对大鼠心肌的保护作用

目的探讨缝隙连接蛋白Cx43是否参与硫化氢后处理减轻离体大鼠心脏缺血/再灌注(I/R)损伤。方法 72只♂SD大鼠随机分为6组(n=12):空白组(Sham组),缺血/再灌注组(I/R组),溶媒组(DMSO组),抑制剂18β-次甘草酸组(AGA组),硫化氢后处理组(NP组),硫化氢后处理+AGA组(N+A组)。采用离体心脏Langendorff灌注模型,平衡灌注20 min后,停灌30 min,复灌60 min。记录平衡末及灌注结束时的心率(HR)、左室舒张末期压(LV-EDP)、左室发展压(LVDP)、左室内压上升最大速率(+dp/dtmax)、左室内压下降最大速率(-dp/dtmax);灌注结束时,TTC染色法检测心肌梗死面积;Western blot半定量线粒体和胞质总的Cx43(total connexin 43,tCx43)和磷酸化Cx43(phosphorylated connexin 43,pCx43)表达水平。结果平衡灌注末各组间心功能指标差异无统计学意义。再灌注后,与I/R组比较,NP组明显改善再灌注损伤心功能的各项指标(P<0.05),减少心肌梗死面积[(24.4±4.8)%vs(49.4±4.2)%,P<0.05];tCx43表达在线粒体中明显升高,胞质中明显降低,pCx43表达线粒体中明显升高,胞质中明显降低。AGA逆转了硫化氢后处理产生的心肌保护效应及tCx43和pCx43在线粒体中表达的增加(P<0.05)。结论缝隙连接蛋白Cx43参与了硫化氢后处理减轻离体大鼠心脏I/R损伤过程。

Protective effects of Cx43-mediated exogenous hydrogen sulfide postconditinoing on rat hearts

Aim To investigate whether connexin 43(Cx43) mediated hydrogen sulfide postconditioning protects isolated rat hearts against ischemia/reperfusion(I/R)injury.Methods 72 male SD rat hearts were isolated and linked to the Langendorff apparatus.They were randomly divided into 6 groups(n=12):sham group(Sham),ischemia /reperfusion group(I /R),DMSO group(DMSO),18β-AGA group(AGA),hydrogen sulfide postconditioning group(NP),and hydrogen sulfide with 18β-AGA group(N + A).The heart rate(HR),the left ventricular diastolic pressure(LVEDP),the left ventricular developed pressure(LVDP),the maximum rate of increase or decrease of left ventricular pressure(±dp/dtmax) were recorded at 20 min of equilibrium and 60 min of reperfusion respectively.Myocardial infarct size was measured by triphenyl tetrazolium chloride(TTC) staining.The expression of total Cx43(tCx43) and phosphorylated Cx43(pCx43) in mitochondria and cytosol were determined with Western blot analysis at the end of reperfusion.Results There were no differences in baseline hemodyamics observed among the experimental groups(P>0.05).After reperfusion,compared with I/R group,NP group had better hemodynamics,the myocardial infarct size was much lower(P<0.05),the expression of tCx43 in mitochondria increased significantly,but decreased significantly in cytosol,the expression of pCx43 was same to tCx43.However,18β-AGA abolished the cardioprotective effects offered by hydrogen sulfide postconditioning and decreased tCx43 and pCx43 expression in mitochondria(P<0.05).Conclusion Exogenous hydrogen sulfide postconditioning effectively protects isolated rat hearts against ischemia and reperfusion injury via activating Cx43.