[Prolongation of the effective refractory period on isolated guinea pig atria by some anti-arrhythmia agents: relevance in a comparison of their potentialities].

The effects of bepridil, nifedipine, verapamil, lignocaïne and amiodarone on the atrial effective refractory period were investigated in the guinea-pig. The observed results permitted elucidation of a remarkable activity by both nifedipine and verapamil, and by bepridil and lignocaïne. In contrast, in the experimental conditions, no activity was detected with amiodarone up to concentrations of 10(-4) M. The efficacity rating of the test compounds is not reflected by their anti-arrhythmic efficacity as demonstrated in vivo in the animal, nor by their therapeutic anti-arrhythmic efficacity as reported in the clinical literature. However, this efficacity rating may be related to the interaction of the compounds with the transmembrane sodium or calcium movements.