To investigate the effect of oxymatrine (OMT) on ventricular arrhythmia (VA) induced by myocardial infarction (MI) in rats and explore the possible mechanism.

Seventy-five healthy male SD rats were randomly divided into a sham operation group, an MI group, and an OMT intervention group, with 25 rats in each group. MI was induced by ligation of the left anterior descending coronary artery in the MI group and OMT group. OMT (100 mg/kg) was administered in the OMT group at two weeks before and two weeks after the establishment of the model. At the end of drug intervention, echocardiography was used to evaluate left ventricular function. The levels of NT-proBNP and hs-TnT in plasma were detected by ELISA. Cx43 mRNA and protein expression in the myocardium weas detected of by RT-PCR and Western blot, respectively. VA was induced by burst stimulation.

The levels of NT-proBNP and hs-TnT in the OMT group were significantly lower than those in the MI group [(256.45±38.55) ng/L vs (371.93±41.23)ng/L, (89.55±13.39)ng/L vs (132.63±20.12)ng/L; P＜0.01]. The relative expression of Cx43 mRNA in the sham, MI, and OMT group was 0.93±0.16, 0.47±0.06 and 0.71±0.12 respectively, the relative expression of Cx43 protein in the three groups was 0.77±0.11, 0.50±0.07 and 0.61±0.08, respectively, and the relative expression of p-Cx43 protein was 0.62±0.09, 0.32±0.05 and 0.50±0.07 respectively; the differences among the three groups were statistically significant (P＜0.05 for all). In addition, the VA induction rate in the OMT group was significantly lower than that of the MI group (21.4% vs 64.3%, P＜0.05).