Electrophysiological effects of cyclovirobuxine D on the ventricular papillary muscle of rats

OBJECTIVE To explore the electrophysiological effects of cyclovirobuxine D (CVB-D) on the isolated right ventricular papillary muscle of rats. METHODS Transmembrane potentials were recorded with conventional glass microelectrodes. RESULTS CVB-D did not show significant influence on all parameters of action potential within the concentration range of 0.3-3.3 μmol·L-1, while CVB-D prolongated action potential duration in dose-dependent way within the concentration range of 13.3 - 63.3 μmol·L-1 , mainly APD50 , APD70 and APD90 . Within the concentration range of 33.3 - 63.3 μmol·L-1 , CVB-D depressed rest potential (RP) , action potential amplitude(APA) and the maximum rate of depolarization (Vmax) in dose-dependent manner. Meanwhile, CVB-D prolongated APD50 , APD70 and APD90 time-de-pendently at 20 μmol·L-1, i.e. ,the primary action was attained at 10 min, and the strongest action reached at about 30 min. Thereafter, these parameters of action potential were hold at certain levels for at least 60 min. CONCLUSION CVB-D not only prolongated APD in dose-dependent and time-dependent manner, but also prolongated ERP and the ratio of ERP/APD, which denoted its antiarrhythmic action.