糖尿病兔心房电生理及L型钙电流的变化

目的研究糖尿病时心房电生理参数、L型钙电流(ICa,L)变化,探讨糖尿病引起心房颤动(简称房颤)的机制。方法本研究分为离体电生理实验和全细胞膜片钳实验两部分,每部分均分为糖尿病组和对照组。糖尿病兔采用四氧嘧啶诱导。每组各8只兔,饲养8周,离体电生理部分在建立Langendorff灌流的离体兔心脏模型后,测量心房间传导时间(IACT)、高位右房、高位左房、低位左房有效不应期(AERP)、AERP的离散度(AERPD)、应用Burst刺激观察房颤诱发情况;膜片钳实验采用酶解法分离单个心房肌细胞,采用全细胞膜片钳技术记录ICa,L。结果与对照组比较,糖尿病组IACT延长(37.66±8.88 ms vs 27.70±2.12 ms),AERPD增大(28.37±7.52 ms vs 11.62±5.60 ms);房颤诱发率升高(6/8 vs 1/8);心房肌细胞ICa,L最大电流密度显著增加(8.94±3.81 pA/pF vs 5.16±1.10 pA/pF),P均<0.05。结论糖尿病时存在心房电重构。

Alterations of cardiac electrophysiology and L-type calcium current in alloxan-induced diabetic rabbits

Objective To evaluate the potential relationship between atrial electrophysiological and L-type calcium current(ICa,L) changes and elucidate the underlying mechanisms for the development of atrial fibrillation(AF).Methods This experiment was divided into two parts.There were 8 alloxan-induced diabetic rabbits and 8 age-matched controls in each part.In the first part,isolated Langendorff perfused rabbit hearts were prepared to evaluate high right atrium(HRA),high left atrium(HLA),left atrial appendage(LLA) refractory effective period(AERP) and its dispersion(AERPD),interatrial conduction time(IACT) and vulnerability to AF.In the second part,using whole-cell voltage-clamp techniques,ICa,L was measured in left atrial myocytes isolated from alloxan-induced diabetic rabbits and age-matched controls.Results IACT was prolonged(37.66±8.88 ms vs 27.70±2.12 ms),and AERPD was increased in diabetic rabbits(28.37±7.52 ms vs 11.62±5.60 ms) compared with controls.Inducibility of AF in diabetic group was significant higher than that in controls(6/8 vs 1/8).The density of ICa,L current in diabetic myocytes was significantly higher than that in the control(8.94±3.81 pA/pF vs 5.16±1.10 pA/pF),P<0.05.The control and diabetic myocytes showed no significant differences with respect to membrane capacitance.Conclusions Atrial electrical remodeling is found to be existent in diabetic rabbits.