Abstract

The relative role of beta1- and beta2-adrenoceptors in the regulation of blood pressure and plasma renin at rest and during exercise was studied in 17 normal male volunteers. They performed three graded and uninterrupted exercise tests until exhaustion after being pretreated during 3 consecutive days with a placebo, with a predominantly b1-blocker (Atenolol), or with a predominantly beta2-blocker (ICI 118551). Both drugs caused a decrease of heart rate. ICI 118551 did not affect blood pressure at rest, but during exercise diastolic blood pressure was higher than after a placebo. Atenolol lowered systolic blood pressure at rest and suppressed the exercise-induced increase in systolic blood pressure. At rest and during exercise plasma renin activity was lowered by predominantly beta1-blockade and unchanged during beta2-antagonism. After atenolol the urinary excretion of aldosterone was decreased but the plasma adolsterone concentration was not changed. ICI 118551 did not alter plasma or urinary aldosterone. Our results therefore provide further evidence that the adrenoceptors mediating the release of renin at rest and during exercise in humans are partially of the beta1-subtype. Predominantly beta1- and beta2-blockade seems to have a differential effect on blood pressure. Verf.-Referat