糖尿病大鼠心肌电学的改变及环维黄杨星D对其电生理的影响

目的：观察糖尿病大鼠心肌电学变化特点，探讨环维黄杨星D(CVB-D)对糖尿病心肌电生理的影响。 方法： 以SD雄性大鼠尾静脉注射四氧嘧啶(alloxan,50 mg·kg^-1)复制糖尿病模型，选择以年龄相匹配的SD雄性大鼠作为对照组。2周后，记录大鼠体表心电图和右心室乳头肌跨膜电位，观察CVB-D对跨膜电位的影响。 结果： 糖尿病造模后第2周时，心率明显减慢于对照组，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<0.01）,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。CVB-D具有剂量依赖效应，在13.3-63.3 μmol·L^-1范围内呈剂量依赖性地延长糖尿病大鼠和对照组大鼠APD30、APD50、APD70和APD90，对糖尿病大鼠APD延长作用更大。在33.3-63.3 μmol·L^-1浓度范围内，CVB-D呈剂量依赖性抑制糖尿病大鼠和对照组大鼠的静息电位(RP)、动作电位幅值（APA）和0期最大去极化速度（Vmax），但对糖尿病组抑制更大。研究结果还显示，CVB-D还具有时间依赖效应，当20 μmol·L^-1灌流心室肌10 min后开始出现作用，对照组到40 min左右作用达高峰，而糖尿病组40 min后仍继续延长。 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。CVB-D可进一步延长糖尿病大鼠的APD，抑制其RP、APA、OS以及Vmax，作用较对照组明显。

Electrophysiological changes in rat ventricular myocardium of experimental diabetes and action of CVB-D

AIM: To investigate the electrophysiological changes of diabetic myocardium and effects of cyclovirobuxine D (CVB-D) on its electrophysiology. METHODS: Diabetes was induced in male SD rats, using a single injection of alloxan into tail vein. Untreated age-matched animals were used as controls. Animal electrocardiogram (ECG) was recorded by 2 weeks. Effects of CVB-D on isolated right ventricular papillary muscle from experimental diabetic rats and control group were observed by recording the transmembrane potentials with conventional glass microelectrodes. RESULTS: QT intervals in ECG and action potential duration (APD) at all levels were significantly lengthened in myocardium from week 2 of diabetes. Within the concentration of 13.3-63.3 μmol·L^-1, CVB-D prologated APD of diabetes in dose-dependent manner and more than that of control. Within the concentration of 33.3-63.3 μmol·L^-1, CVB-D depressed RP, APA, Vmax and OS of diabetes in dose-dependent way and more than that of control. In addition, CVB-D at concentration of 20 μmol·L^-1 prologated APD in a time-dependent manner. The most prologation of APD was attained about 40 min in control, while more than 40 min in diabetes. CONCLUSION: The results show that QT intervals in ECG and APD at all levels are significantly lengthened in myocardium from week 2 of diabetes. CVB-D prolongates APD and inhibits RP, APA, OS and Vmax more in diabetes than in control.