A New Class III Antiarrhythmic Drug Niferidil Prolongs Action Potentials in Guinea Pig Atrial Myocardium via Inhibition of Rapid Delayed Rectifier.

A new class III antiarrhythmic drug niferidil (RG-2) has been introduced as a highly effective therapy for cases of persistent atrial fibrillation, but ionic mechanisms of its action are poorly understood. In the present study, the effects of niferidil on action potential (AP) waveform and potassium currents responsible for AP repolarization were investigated in guinea pig atrial myocardium. APs were recorded with sharp glass microelectrodes in multicellular atrial preparations. Whole-cell patch-clamp technique was used to measure K In multicellular atrial preparations, 10 Niferidil prolongs APs in guinea pig atrial myocardium via inhibition of I