Abstract: 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.

Key words: myocardial ischemia, sudden death, Cx43, arrhythmia, intercalated disc