Effect of anti-arrhythmic drug changrolin on fast and slow response potentials of myocardial cell of rats

Effects of changrolin (4-{3’,5’-bis [N-pyrrolidinyl methyl]-4’-hydroxyanilino} quinazoline) on the normal fast action potential and evoked slow response of ventricular cells in vitro were studied by intracellular capillary glass electrode. The amplitude and maximal depolarization rate of phase O (Vmax) of fast action potential were lowered, the duration of action potential shortened, the effective refractory period prolonged, and the excitability decreased, but the resting potential remained practically unchanged. For slow response, the amplitude, depolarization rate of action potential and particularly the effective refractory period were increased, the duration of action potential was prolonged both for APD50 and APD100 after changrolin 30 min (from 43±15 to 67±17 ms and 69±19 to 96±19 ms, respectively). It is considered that changrolin may be a new type of anti-arrhythmic drug.