ACUTE COMBINED ALPHA-ADRENERGIC AND BETA-ADRENERGIC-BLOCKADE IN ESSENTIAL HYPERTENSION - EFFECTS ON BLOOD-PRESSURE, RENAL-FUNCTION, RENIN, AND ALDOSTERONE

In seven patients with uncomplicated essential hypertension the effects of an acute alpha-adrenergic blockade, alone and combined with a chronic beta-adrenergic blockade, on blood pressure, renal function as measured by standard clearance methods, plasma renin activity, and plasma aldosterone were evaluated. Acute alpha-adrenergic blockade with phentolamine (20 mg by intravenous infusion) significantly enhanced the antihypertensive effect of chronic beta-adrenergic blockade with slow-oxprenolol (160 mg/day×14 days) (-14.5% versus -7.4% for pulse pressure, -12.4% versus -6.0% for diastolic pressure, 2α<0.05). Under combined adrenergic blockade renal plasma flow increased, glomerular filtration rate and filtration fraction decreased (2α<0.05 each), whereas the fractional clearances of sodium, potassium, free water, and solute load remained unchanged. The activation of the renin-angiotensin-axis, elicited by alpha-adrenergic blockade alone, was suppressed by the preceding beta-adrenergic blockade. These findings demonstrate a favourable antihypertensive action of a combined blockade of alpha-und beta-adrenergic receptor sites without untoward side effects on renal function or the renin-angiotensinaxis. © 1979 Springer-Verlag.