A 10 min ligation of the left anterior descending coronary artery in anaesthetized pigs resulted in ventricular fibrillation (VF) in 70% of control and propranolol-treated animals. Felodipine (10 nmol kg-1) not only reduced ventricular ectopic activity by 90%, but also completely abolished VF. When a second occlusion was applied after 20 min of reperfusion, felodipine was less effective against VF, possibly due to decreasing felodipine concentrations or only a transient increase in VF threshold.