Plasma catecholamines, renin and aldosterone during combined alpha- and beta- adrenoceptor blockade in patients with severe arterial hypertension.

Arterial blood pressure and plasma catecholamines, renin activity and aldosterone concentration in 12 patients with severe essential hypertension were studied before and after combined alpha- and beta- adrenoceptor blockade induced by oral labetalol treatment for 2 months. Frusemide in a fixed dose was employed as a basic antihypertensive agent throughout the study. Blood pressure was adequately controlled in only 6 patients. Mean body weight increased by 1.8 kg and there was a rise in body weight which was inversely correlated with the fall in standing mean blood pressure. The mean plasma noradrenaline concentration decreased from 0.30 to 0.20 ng/ml, whereas plasma adrenaline did not change significantly. Plasma renin activity and aldosterone concentration varied greatly, but the mean values did not change significantly. Change in body weight was correlated inversely with changes in plasma noradrenaline and renin. The results suggest that labetalol, through its combined alpha- and beta- adrenoceptor blocking action, induces a rise in body weight, probably due to sodium and fluid retention, which partly counterbalances its anti-hypertensive effect and partly modifies both renin and sympathetic nervous activity.