[Effects of sodium vanadate on action potentials of guinea pig papillary muscles]

Sodium vanadate (NaVO3, 800 mumol/L) diminished the plateau phase and the action potential duration of the action potentials in guinea pig ventricular fibers (VF). 200 mumol/L also reduced the maximal rate of depolarization of slow action potentials in the partial depolarized VF under high K superfusion and inhibited the delayed after depolarization induced by adrenalin. It is suggested that NaVO3 may inhibit the slow channel current and does not reduce the sodium pump activity in VF significantly when it was used extracellularly.