Effects of tanshinone IIA on ventricular arrhythmias induced by acute myocardial ischemia

Objective To investigate the effects of Tanshinone Ⅱ A (extracted from Chinese herb medicine Salvia miltiorrhiza Bge.) on ventricular arrhythmias of rabbit hearts induced by ischemia in order to illuminate its mechanism of anti-arrhythmia.Methods Thirty rabbits were randomly (random number)divided into normal group,ischemic group and Tanshinone Ⅱ A group.Model of wedge shaped mass of rabbit left ventricular myocardium with coronary perfusion was prepared,and then by using floating glassy microelectrode,the trans-mural ECG,QT interval,the trans-mural dispersion of re-polarization (TDR) and trans-membrane action potentials from both endocardium and epicardium were simultaneously and wholly recorded.The incidence of ventricular arrhythmia in myocardium was observed after ischemia for thirty min.Results Under the condition of acute ischemia,compared with normal group,the incidence of ventricular arrhythmia and TDR were significantly increased in ischemia group (P ＜ 0.01),while incidence of ventricular arrhythmia and TDR were significantly reduced in tanshinone ⅡA group compared with ischemia group (P ＜ 0.05).The incidences of ventricular arrhythmia in normal,ischemia and Tanshinone Ⅱ A groups were 0/10,9/10 and 2/10 respectively.Conclusions Tanshinone Ⅱ A prevents ventricular arrhythmia and reduces TDR significantly in ischemic rabbit hearts. Key words: Tanshinone Ⅱ A;  Ischemia;  Ventricular arrhythmia;  Transmural dispersion of repolarization;  Action potential;  Electrophysiology ;  Transmural ECG;  Rabbit