Effects of resibufogenin on the action potential of myocardial fibers of the dog and guinea pig

The electrophysiological actions of resibufogenin(RBG) on Purkinje fiber(PF) specimens of 46 dogs showed that there were 1)progressive decreases in action potential amplitude, resting potential, Vmax,action potential duration and effective refractory period; 2) increases in the slope of depolarization of phase 4 and the automatic rhythmicity of PF. The spontaneous action potential was sometimes induced by RBG. The effects of RBG on PF were concentration-dependent. The minimum effective concentration was 0.6 microM. The effects of RBG on the ventricular fibers(VF) of dogs ang guinea pigs were similar to those on dog PFs.There were similar effects in the different tissues(PF and VF) of dogs and the same tissue of different species of animals (dog and guinea pig) by RBG.