Atrial APD prolongation caused by the upregulation of RAGE and subsequent INaL increase in diabetic patients
Diabetes mellitus (DM) is a risk factor for the development of atrial fibrillation (AF). The action potential duration (APD) has been demonstrated to be prolonged in the atrium of diabetic mice. In contrast, the APD is generally shortened in AF patients. It is unclear what change occurs in the atrial APD of diabetic patients. In this study, we explore the APD change of atrial myocytes from diabetic patients and the underlying molecular mechanisms. The whole-cell patch-clamp technique is used to detect single-cell electrical activity in diabetic and nondiabetic human samples. The results show that both APD50 and APD90, the APD at 50% and 90% repolarization, are increased in diabetic patients compared with those in nondiabetic controls. The density of late sodium current (INaL) in the atrial myocytes of diabetic patients is greater than that in the myocytes of nondiabetic patients. The expression of receptor for advanced glycation end products (RAGE) is increased in the atria of diabetic patients. In cultured HL-1 cells, high glucose (HG) treatment increases INaL, and the expression of RAGE prolongs APD. The siRNA-mediated knockdown of RAGE reduces the INaL and shortens the APD. The APD is prolonged in the atria of diabetic patients because of the upregulation of RAGE and the subsequent increase in INaL. Our findings provide novel insights into atrial electrical remodeling in diabetic patients.