EFFECTS OF VISCUM-COLORATUM FLAVONOIDS ON FAST-RESPONSE ACTION-POTENTIALS OF HEARTS

The effects of the total flavonoids of Viscum coloratum (VCF) on the f ast response action potentials (FAP) of canine Purkinje fibers and gui nea pig ventricular papillary muscles were studied by glass-microelect rode technique; The effects of VCF on the ionic currents through cellu lar membrane were analysed with selective ion blockers (CsC1, verapami l, and TEA(+)), respectively. VCF (100 mu g.ml(-1)) accelerated the re polarization of FAP and increased Delta ERP/Delta AFD ratio, which wer e related to decreasing I-si and increasing I-x. It was suggested that the antitachyarrhymic mechanism of VCF was attributed to prolonging E RP relatively and to abolishing reentrant excitation.