Effect of restacorin on the early and delayed after depolarization in dog Purkinje fibres.

The effect of restacorin and flecainide on the early afterdepolarization (EAD) and on the delayed afterdepolarization (DAD) was studied in dog cardiac Purkinje fibers by applying the conventional microelectrode technique. Restacorin and flecainide at 5 microM concentration partially abolished EAD. Further increase of the concentrations of the drugs to 10 microM EADs were completely abolished. The amplitude of DADs were significantly decreased by both restacorin (9.9 +/- 2.1 mV v.s. 2.9 +/- 1.8 mV, p < 0.01, n = 5) and flecainide (11.1 +/- 1.3 mV v.s. 0.6 +/- 0.6 mV, p < 0.01, n = 7). These results suggest that the well-established antiarrhythmic effect of restacorin and flecainide at least partially may be explained by their beneficial action against triggered abnormal automaticity.