糖尿病大鼠心肌电学的改变与腺苷的作用

Effect of adenosine on electrophysiological changes of ventricular myocardium in rats with experimental diabetes

目的 :探讨糖尿病心肌病的心肌电生理改变以及腺苷 (ADO)对其电生理的可能作用。方法 :以 SD雄性大鼠复制糖尿病模型 ,选择健康成年 SD雄性大鼠作为对照组 ,6周时记录大鼠体表心电图和右心室乳头肌跨膜电位 ,观察 ADO对跨膜电位的影响。结果 :大鼠糖尿病成模后第 6周 ,体表心电图 QT间期和右室乳头肌动作电位时程 (APD)各水平均明显长于对照组大鼠 (P<0 .0 1) ;而静息膜电位 (RP)、动作电位幅度 (APA)和超射值 (OS) ,以及 0期去极化最大速率 (Vmax)均无明显变化。经 10～ 4 0 0 μmol/L ADO灌流 ,糖尿病组大鼠和对照组大鼠右心室乳头肌跨膜电位各参数均无明显作用 ,当 ADO浓度增加到 5 0 0 μmol/L时 ,对照组大鼠右心室乳头肌 APD3 0 、APD50 、APD70 及 APD90 轻度缩短 (P<0 .0 5 ) ,而对糖尿病组大鼠 APD无明显影响。结论 :糖尿病大鼠右室乳头肌动作电位时程和 QT间期明显延长 ,而 ADO(10～ 5 0 0μmol/L )对糖尿病大鼠过长的

Objective: To investigate the electrophysiological changes of ventricular myocardium of rats with experimental diabetes and the effect of adenosine on its electrophysiology. Methods: Diabetes was induced in male SD rats, using a single injection of alloxan into tail vein. Untreated animals were used as controls. The electocardiograms (ECG) were recorded 6 weeks after diabetes was induced. Effects of adenosine on ventricular myocar dium in diabetic rats and controls were observed by measuring the transmembrane potentials with conventional glass microelectrodes. Results: QT interval in ECG and action potential duration (APD) at all levels (APD 30 ,APD 50 ,APD 70 and APD 90 ) were significantly prolonged in right ventricular papillary muscle 6 week after diabetes was induced. No differences were observed in the resting membrane potential(RP),action potential amplitude(APA) and overshoot(OS) as well as the maximum rate of depolarization (V max ) between the diabetic rats and control rats. At concentration of 10～400 μmol/L, ADO had little influence on all transmembrane potential parameters of right ventricular papillary muscle in diabetic rats and controls. At 500 μmol/L,ADO shortened APD 30 ,APD 50 ,APD 70 and APD90 of control group,while having no effect on diabetic rats. Conclusion: QT interval in ECG and APD at all levels are significantly prolonged in right ventricular papillary muscle of experimentally induced-diabetic rats.