title: Electrophysiological effects of imipramine on bovine ventricular muscle and Purkinje fibres.
abstract: 1 The effect of imipramine in concentrations between 0.01 microM and 50 microM has been studied on bovine Purkinje fibres and ventricular muscle transmembrane potentials. 2 In electrically stimulated fibres, imipramine had no effect on the resting membrane potential, but decreased the action potential amplitude, overshoot and maximum rate of depolarization (Vmax). 3 In Purkinje fibres, imipramine also decreased the conduction velocity and shifted the membrane responsiveness and recovery time curves downward and to the right. 4 In both Purkinje fibres and ventricular muscle, imipramine decreased the amplitude of phase 2 and prolonged phase 3. In Purkinje fibres, imipramine did not alter the action potential duration (APD) but prolonged the effective refractory period (ERP). In ventricular muscle, at concentrations higher than 1 microM imipramine shortened both the APD and the ERP and made the ERP long as compared to APD. 5 Imipramine decreased the slope of phase 4 diastolic depolarization in spontaneously beating Purkinje fibres. 6 These properties of imipramine are quite similar to those of quinidine or procainamide (class 1 antiarrhythmics). The mechanisms responsible for the cardiac effect of imipramine are discussed.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002417:Cattle; D006321:Heart / Q000187:drug effects*; D006329:Heart Conduction System / Q000187:drug effects*; D007099:Imipramine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009431:Neural Conduction / Q000187:drug effects; D011690:Purkinje Fibers / Q000187:drug effects*
chemical_list: D007099:Imipramine