Expression of Connexin 43 in the Myocardium in Sudden Unexplained Nocturnal Death Syndrome
Korean J Leg Med 2016;40:33-38

Department of Forensic Medicine, Pusan National University School of Medicine, Yangsan, Korea, Department of Physiology, Inje University College of Medicine, Busan, Korea

gyhuh@pusan.ac.kr

Sudden unexplained nocturnal death syndrome (SUNDS) occurs predominantly in Southeast Asian people including Koreans. SUNDS is problematic for forensic pathologists because the diagnosis depends on the “exclusion of diagnosis.” Moreover, the pathogenesis of SUNDS is still unclear although some cases are known to be intimately related to the Brugada syndrome. Connexin 43 (Cx43) is a principal protein of gap junction in adult cardiac myocytes, being distributed to the intercalated discs and phosphorylated in normal condition. Ischemia and hypoxia alter the expression of total Cx43 (tCx43) resulting in redistribution of non-phosphorylated Cx43 (npCx43) to the sarcoplasm or lateral cell borders of cardiac myocytes by continuing dephosphorylation. This study aimed to compare the immunoexpression pattern of Cx43 in the cardiac myocytes of SUNDS and ischemic heart disease (IHD). The study group was 26 cases of SUNDS and the control group of 24 cases of IHD with severe coronary atherosclerosis, showing no myocardial ischemic change. There was a significantly different expression of both tCx43 and npCX43 between the SUNDS and IHD group. A greater reduction in both tCx43 and npCx43 and a more delayed redistribution pattern was seen in the myocardium of SUNDS when compared with IHD. In conclusion, these results suggest that the reduced Cx43 expression in SUNDS may be inherent and indicate a risk of arrhythmia.

Key Words: Brugada syndrome; Connexin 43; Immunohistochemistry; Myocardium; Myocardial ischemia