Cardiac electrophysiological effects of citalopram in guinea pig papillarymuscle - Comparison with clomipramine

The effect of citalopram, a selective serotonin reuptake inhibitor (SSRI) a ntidepressant, was studied on cardiac action potential configuration and co mpared with that of the tricyclic antidepressant (TCA) clomipramine. Conven tional microelectrode techniques were used in right ventricular papillary m uscle preparations of the guinea pig. Citalopram caused a concentration-dep endent (10-100 mu M) shortening of action potential duration (APD), depress ion of plateau and overshoot potential, and reduction of maximum velocity o f depolarization (V-max). No significant changes in resting membrane potent ial were observed. Similar results were obtained with clomipramine; however , reduction of V-max and overshoot was more pronounced with clomipramine, w hereas citalopram caused relatively greater shortening of APD. Effects of b oth drugs were partly reversible. The results indicate that the SSRI antide pressant citalopram, similarly to TCA compounds, alters cardiac action pote ntial configuration in guinea pig ventricular muscle, probably owing to inh ibition of cardiac Na+ and Ca2+ channels. Differences in cardiac side effec ts of the two drugs may be related to their different actions on cardiac ac tion potential configuration. (C) 2000 Elsevier Science inc. All rights res erved.