Plasma renin concentration in essential hypertension during beta-adrenergic blockade and vasodilator therapy.

Plasma renin concentration (PRC) was measured in 46 patients with essential hypertension before and after treatment for 4 weeks with alprenolol 600-1200 mg daily. In 27 of these patients PRC was measured after 4 weeks of combined treatment with alprenolol and hydralizine. During alprenolol treatment PRC and blood pressure were reduced, but the changes were not correlated. Alprenolol treatment caused similar blood pressure reductions in patients with high and low PRC, and the antihypertensive efficacy of beta-adrenergic blocking agents could not be predicted from the pretreatment PRC. When beta-adrenergic blockade was supplemented with hydralazine, blood pressure was further reduced, but PRC remained unchanged. Although a causal relationship between blood pressure reduction and suppression of renin, production might exist at low doses of beta-adrenergic blocking agents, the present study did not indicate such a relationship when higher doses were used. It was shown that alprenolol inhibited the increase in PRC usually induced by hydralazine, but it is not known whether this was important for the effectiveness of the fall in blood pressure produced by hydralazine.