Why the study?
Does imipramine alter transmembrane potentials in bovine Purkinje fibres and ventricular muscle?
Does imipramine alter transmembrane potentials in bovine Purkinje fibres and ventricular muscle?
Imipramine exhibits electrophysiological properties in bovine cardiac tissue that are similar to class 1 antiarrhythmics like quinidine or procainamide.
Imipramine's class I-like effects in bovine tissue are hypothesis-generating; human studies needed before any clinical consideration.
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.
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A 1980 study studied this question.
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