Responses of catecholamines and blood pressure to beta-blockade in diuretic-treated patients with essential hypertension.

Twenty patients (mean age 49 +/- 4 (SEM) yr) with mild to moderate essential hypertension were studied during placebo conditions, following 6 weeks of chlorthalidone monotherapy and 6 to 28 weeks of combined beta-blocker-chlorthalidone treatment, or vice versa. Compared to chlorthalidone therapy alone, addition of a beta-blocker to this diuretic caused a further blood pressure reduction in 11 patients (Responders); in 9 patients addition of a beta-blocking agent failed to further reduce blood pressure (Non-responders). Supine and upright plasma renin, aldosterone, norepinephrine and epinephrine levels and catecholamine excretion rates were always comparable between Responders and Non-responders. In both groups plasma and urinary norepinephrine or epinephrine values were not significantly altered following addition of a beta-blocker; heart rate and plasma renin activity were decreased in both groups to a similar extent. It is concluded that the antihypertensive mechanism of beta-blockers given to diuretic treated patients with essential hypertension is independant of renin and not associated with changes in plasma or urinary catecholamines.

RCT Entities:   Population Interventions Outcomes