Effects of chlorpromazine on the isolated perfused guinea pig heart.

Chlorpromazine altered the mechanical and electrical activity of the isolated perfused guinea pig heart. While its effects on coronary flow were variable, chlorpromazine increased resting diastolic isometric tension and decreased the isometric systolic tension developed by spontaneously beating hearts. Heart rate was also decreased. The drug depressed conduction through the His-Purkinje system and ventricular muscle to a greater extent than it did atrial conduction time and AV nodal conduction time. From our data, we concluded that the greatest depressant action of chlorpromazine on the electrical activity of the isolated perfused guinea pig heart occurred within the specialized ventricular conduction system and ventricular muscle.