Prolonged Administration of Hydrochlorothiazide on Cardiac Function in Beagle Dogs

Conclusions

Chronic administration of hydrochlorothiazide (10 mg/kg, po for 12 months) to beagle dogs failed to produce any alterations in blood pressure and heart rate, despite a significant reduction in cardiac output, stroke volume, and stroke work. Analysis of ventricular function curves indicates a diminution in contractility of the myocardium in the treated animals. It is concluded from this investigation that the adverse effects of HCT on the myocardium in the face of increased total peripheral resistance noted in this study may warrant careful reevaluation of this agent in cardiovascular therapy.

This study was supported by Public Health Service Grant GM-15587. The authors express their appreciation to Dr. John E. Baer of Merck Institute of Therapeutic Research, West Point, PA, for generously supplying hydrochlorothiazide, and to Messrs. Charles Parham and David Snyder for their valuable technical assistance.