Acute effects of alpha-methyldopa on mean blood pressure and plasma renin activity.

a-Methyldopa significantly lowered mean blood pressure and plasma renin activity in dogs anesthetized with sodium pentobarbital. After unilateral ligation of the right renal vessels and contralateral denervation of the kidney, a-methyldopa significantly lowered mean blood pressure but did not change plasma renin activity. It was concluded that a-methyldopa acutely lowers plasma renin activity via an action mediated through the adrenergic nervous system. However, this decrease in plasma renin activity is not responsible for the decrease in mean blood pressure produced by the drug.