Connexin43 expression and distribution in left atrial tissue from patients with combined dilated cardiomyopathy and atrial fibrillation

AIM:To investigate Connexin 43 (Cx43) expression, phosphorylation and distribution in atrium of dilated cardiomyopathy (DCM) patients with or without atrial fibrillation (AF) and to demonstrate the relationship between Cx43 and AF. METHODS: Among 18 DCM patients who underwent heart transplantation, eight patients had sinus rhythm (SR) at the time of surgery (SR group) without AF history. Six patients maintained SR with AF history (AF+SR group) and four patients persisted with AF(AF+AF group). Echocardiography was performed to determine left atrial diameter (LAD) and cardiac function. Expressions of Cx43 and phosphorylated Cx43 at the site of Ser368 (pSer368Cx43) were detected by immunofluorescence staining and Western blot. RESULTS: No significant difference was observed in LAD and cardiac function among the three groups and no significant difference was seen in the level of Cx43 and pSer368Cx43 between SR group and AF+SR group. In contrast, total Cx43 (TCx43) in AF+AF group was obviously higher than in the SR group and AF+SR group. Phosphorylated Cx43 (pCx43) increased in atrial tissue of AF+AF group and redistributed from intercalated disk to the lateral borders of myocytes. CONCLUSIONS: AF rhythm in DCM may be accompanied by abnormalities in atrial Cx43 expression, phosphorylation and distribution.