Changes Of Electrical And Mechanical Properties Of Diabetic Rat Ventricular Myocardium And Effects Of Cyclovirobuxin-D And Adenosine

[Objective] To explore the probable mechanisms of diabetes-induced arrhythmias. [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. All animals' body electocardiograms(ECG) were recorded by 2, 4, 6 and 8 weeks, respectively. Transmembrane potentials were recorded with conventional glass microelectrodes.[Results]QT and QTC interval in body ECG of diabetic rats were obvious prolongation , Heart rates obviously slowed. Action potential duration(APD) at all level (APD10 APD20 APD30 APD50 APD70 APD90) was significantly lengthened in right ventricular papillary muscle from 2th week of diabetes, at 8th week, APD was more lengthened atany level of repolarization than 2th week. The changes of APD mentioned above was concordant with that changes of blood sugar and cardiosomatic ratio. No differences were observed in the maximum rate of depolarization(Vmax), overshoot (OS) and action potential amplitude(APA) as well as the resting membrane potential(RP) from 2"' to 8th week of diabetes.[Conclusion] The results indicate that prolongation of APD may be prominently responsible for the increased incidence of cardiac re-entry-arrhythmias and sudden death, especially at late stages of diabetes.