Effects of guan-fu base A on fast response action potentials of papillary muscles of guinea pigs

Guan-fu base A is a new alkaloid first isolated from the tuber of Aconitum coreanum in China. The electrophysiological effects of guan-fu base A were examined on the isolated papillary muscles of guinea pigs by glass-microelectrode technique coupled with microcomputer real-time analysis. Guan-fu base A 50 micrograms/ml had less effect on RP, but markedly decreased Vmax and APA of the fast response action potentials. The action potential duration was shortened at all voltage levels and plateau height was lowered. ERP was prolonged relatively and activation voltage became more negative. The inhibition of guan-fu base A on Vmax showed frequency dependent effects. The above results suggested that guan-fu base A could block the fast Na+ channels and exhibited anti-arrhythmic action.