DOSE-DEPENDENT PROARRHYTHMIC AND ANTIARRH YTHMIC EFFECTS OF PROCAINAMIDE IN AN EXPERIMENTAL-MODEL

Isolated coronary perfused right ventricle of the rat heart was reperf used after 20 min of Ischemia. Arrhythmias could be induced by prematu re stimulation during slow-rate reperfusion in 30 of 33 (90%) experime nts. For prevention of these arrhythmias procainamide was used in low (5 mg/l) and high (50 mg/l) concentrations. Proarrhythmic effect defin ed as prolongation of vulnerable period and increase in arrhythmia dur ation was produced by low concentration in 13 of 19 (68%) experiments while high concentration in 8 of 10 (80%) experiments exerted an antia rrhythmic action and prevented arrhythmia inducability. When nonishemi c ventricles were perfused with low concentrations of procainamide (5 mg/l) before ischemia no arrhythmias could be induced.