[Antioxidative action of soyasaponin monomers I, A1, A2, and their inhibitory effects on action potential and beating of myocardiocytes in culture].

Ventricular myocardiocytes from newborn Wistar rats were cultured. Soyasaponin monomers I, A1, A2 2 micrograms.ml-1 added to the culture medium, like nimodipine 1.25 microgram.ml-1, decreased the number of spontaneously beating clusters and the action potential parameters of myocardiocytes, which restored after washing out and were reversed by Ca2+ 80 micrograms.ml-1 or epinephrine 10 micrograms.ml-1, indicating the Ca2+ channel blockade action of the saponin monomers. Adding xanthine 0.42 mmol.L-1 and xanthine oxidase 5.4 nmol.L-1 into culture medium led to the increase of free radical content of the myocardiocytes and the decrease of action potential parameters, which were reversed by I 2 micrograms.ml-1, indicating the antioxidative action of saponin monomer I.