急性心肌缺血猝死例左室心肌Cx43脱磷酸化的免疫组化研究

Immunohistochemical study of Cx43 dephosphorylation in human left ventricular myocardium suf-fered by acute ischemia

目的观察急性心肌缺血所致心性猝死,特别是冠心病猝死者与对照组,左室心肌闰盘上缝隙连接蛋白Cx43磷酸化状态的差异,探讨其在急性心肌缺血心律失常的发生,及其诊断心肌缺血早期病变中的意义。方法应用免疫组化SP技术,检测无明显心肌梗死的冠心病猝死组(组Ⅰ)、其他急性心肌缺血所致心性猝死组(组Ⅱ、Ⅲ)和两对照组(组Ⅳ、Ⅴ,严重颅脑损伤或病理性颅内出血所致急性死亡),共45名死者的左心室局部心肌组织(存档蜡块)中Cx43的磷酸化状态。另选用抗心肌闰盘上粘合连接的主要蛋白Pan-Cadherin的抗体和生物素化菜豆凝集素(PHA-E+L/Bio),分别检测心肌细胞间机械耦联与心肌细胞膜的完整性(后者采用亲和组化技术),以便在实验中与Cx43免疫组化染色结果作比较分析。结果⑴在实验组各例标本的心肌闰盘上磷酸化Cx43明显缺染,少数呈点状弥散于胞浆;但在两对照组中,可见磷酸化Cx43聚集于心肌闰盘处。⑵Pan-Cadherin在各例标本中均表现为心肌闰盘处的强阳性着色。⑶各组标本其心肌细胞膜均显示良好,细胞轮廓清晰可辨。结论急性心肌缺血所致心性猝死者,左室心肌细胞间机械耦联和心肌细胞膜的完整性与对照组相比,无明显改变,但闰盘处主司电耦联的缝隙连接蛋白Cx43却发生了明显的脱磷酸化。这提示,后者可能是急性心肌缺血所?

Objective This study was performed to detect the phosphorylation state of Cx43in human left ven-tricular myocardium among sudden deaths caused by acute myocardial ischemia(AMI)especially sudden coro-nary death(SCD)and control groups.And then evaluate the significance of these findings in diagnosing the early pathological changes of acute myocardial ischemia.Methods Immunohistochemistry(IHC)SP techniques were adopted to detect the phosphorylation state of Cx43in the left ventricular myocardium samples of45deceased,which classified as groupⅠ-SCD,groupⅡ&Ⅲ(other two groups of AMI)and GroupⅣ&Ⅴ(two control groups,sudden death caused by lethal acute cranio-cerebral injury or pathologic intracranial hemorrhage).In addition,we selected anti-Pan-Cadherin(construction protein of adherent junctions on the intercalated disc)and PHA-E+L/Bio,to detect the integration of myocardial mechanical coupling and membranes(applying affinityhisto-chemistry,AHC)respectively.Results⑴Phosphorylated Cx43positive staining was almost invisible in GroupⅠ,ⅡandⅢor scattered in sarcoplasm in few samples;but it was assembling at the IDs clearly in groupⅣandⅤ.⑵Strongly positive staining of Pan-Cadherin could be observed at the IDs and⑶integrated myocardial mem-branes were found in all samples.Conclusion These findings suggested that compared with the control groups,the integration of myocardial mechanical coupling and membranes did not alter in AMI.But Cx43,the key pro-tein of electrical coupling on myocardial gap junctions,occurred dephosphorylation remarkably in AMI.Thus ap-plying IHC techniques to detect the Cx43dephosphorylation in human left ventricular myocardium maybe useful to recognize the onset of arrhythmia in AMI,especially in SCD whose myocardium without apparent morphologi-cal changes.