Ghrelin对糖尿病大鼠心肌动作电位和瞬时外向钾电流的影响
Effects of ghrelin on action potential and transient outward potasium current in streptozotocin-induced diabetic cardiomyopathy rats

摘要：目的 探讨外源性ghrelin对糖尿病心肌病(DCM)大鼠心肌动作电位及瞬时外向钾电流(Ito)的影响。方法 雄性SD大鼠腹腔注射链脲佐菌素(60mg/kg)诱导Ⅰ型DCM模型，并采用全细胞膜片钳技术观察ghrelin对糖尿病大鼠心室肌细胞动作电位及瞬时外向钾电流的影响。结果 与DCM组比较，10-7mmol/L ghrelin明显延长DCM大鼠心室肌细胞5%动作电位时程(APD50)[(12.49±2.32)%；n=7，P=0.037]及APD90[(26.29±5.13)%；n=7，P=0.006]；并明显抑制Ito电流峰值，抑制率[(23.14±3.07)%；n=9，P=0.021]。结论 外源性ghrelin抑制Ito电流而延长DCM大鼠心肌动作电位时程，参与糖尿病大鼠心脏电生理的重构。
ABSTRACT: Objective To study the effects of ghrelin on action potential (AP) and transient outside K+ current (Ito) in ventricular myocytes of diabetic cardiomyopathy (DCM) rats. Methods A rat model of DCM was established by single intraperitoneal injection of streptozotocin (STZ, 60mg/kg), and whole cell patch-clamp technique was used to record the effects of 10-7mmol/L ghrelin on AP and Ito current density in the DCM rat ventricular myocytes. Results Compared to DCM group, Ghrelin of 10-7mmol/L could significantly prolong APD50 [(12.49±2.32)%; n=7, P=0.037] and APD90[(26.29±5.13)%; n=7, P=0.006] and decrease Ito current peak value [(23.14±3.07)%; n=9, P=0.021] in DCM rat ventricular myocytes. Conclusion Exogenous ghrelin is involved in the electrophysiological reconstruction of the heart of diabetic rats by decreasing Ito current and prolonging APD in STZ-induced DCM rat ventricular myocytes