Electrophysiological effects of some antidepressant drugs on canine cardiac Purkinje fibres

The electrophysiological effects of several antidepressant drugs, imipramine, metapramine, mianserin, nomifensine, and amineptine, were studied in canine cardiac Purkinje fibres at concentrations between 10−6 mol·litre−1 and 10−4 mol·litre−1. Metapramine (10−5 mol·litre−1) decreased the action potential amplitude, the action potential duration, and Vmax. In addition, imipramine or metapramine induced a pronounced increase of conduction time and conduction block at 10−4 mol·litre−1, whereas with mianserin and nomifensine a 10−4 mol·litre−1 concentration was necessary to induce a decrease of Vmax and conduction velocity. With the exception of conduction time and action potential duration, amineptine was not able significantly to change the electro- physiological indices of canine Purkinje fibres. The decrease of Vmax observed with imipramine, metapramine, and with high concentrations of mianserin and nomifensine confirms that the antiarrhythmic action of these agents might be related principally to their class I antiarrhythmic effects. The fact that amineptine, which is not antiarrhythmic, does not decrease Vmax reinforces this suggestion.