Effect of Methyldopa Treatment on Cardiac Function and Myocardial Blood Flow in Mongrel Dogs

Conclusions

Administration of methyl-dopa (100 mg/kg, orally twice daily for a period of 3 days) to mongrel dogs produced significant reductions in blood pressure and heart rate. The hypotensive effect of the drug was due to a reduction in peripheral resistance. Methyldopa treatment also produced a significant decrease in coronary vascular resistance. Studies on the left ventricular function indicated that treatment with methyldopa does not compromise the ability of the myocardium to respond to an increased work load. Thus, the beneficial effect of this agent on the myocardial circulation, together with its lack of any detrimental effect on the cardiac function suggest that methyldopa may be an effective agent for the control of hypertension.

The generous supply of methyldopa by Dr. C. A. Stone of the Merck Institute of Therapeutic Research, West Point, Pennsylvania, is greatly appreciated. The authors wish to thank Dr. Regis R. Vollmer for his help; and Ms. Barbara Lewis for excellent preparation of this manuscript. This study was partly supported by USPHS Grant No. HL 17401.