Comparison of the effect of antidepressant drugs on arrhythmias in the isolated rat heart subjected to myocardial ischaemia and reperfusion.

Rat isolated hearts were perfused according to the Langendorff's method. The hearts were prelabelled with 3H-noradrenaline (3H-NA) and the left coronary artery was occluded during 10 min. The liberation of 3H-NA and the development of ventricular arrhythmias were investigated during ischaemia and the following reperfusion period. In control preparations, reperfusion was followed by ventricular fibrillation and a sudden release of radioactivity in the coronary effluent. Antidepressants such as imipramine, metapramine, mianserin and nomifensine prevented reperfusion arrhythmias in a concentration-dependent manner and caused bradycardia. Amineptine, however, was ineffective in preventing reperfusion arrhythmias even in a high concentration, this agent did not decrease heart rate. Nevertheless none of the antidepressants changed the rate of liberation of 3H-NA during the ligation and reperfusion periods. A quinidine like action seems the most appropriate explanation for the cardiac effects of these antidepressant drugs.