Decrease in plasma noradrenaline levels following long-term treatment with prindolol in patients with essential hypertension

Abstract

15 patients (4 females, 11 males, 21 to 55-year old) with mild to moderate essential hypertension (EH) were treated with placebo for two weeks and thereafter with increasing doses of prindolol (15 to 38 mg/day in the mean) and kept on a mean maintenance dosage of 32 mg/day for an average of 16 weeks in all. Blood pressure (BP), heart rate und plasma noradrenaline (PNA) concentrations were measured under standardized conditions (supine, standing, walking) at the end of two weeks on placebo and after the experimental treatment period. The results were compared to those of a group of 15 normotensive untreated control subjects (NS): after an average of 16 weeks on prindolol BP fell from 163/113 mm Hg to 129/91 mm Hg in the mean. PNA levels in EH before prindolol were significantly higher than in NS (supine: 272 +/- 22.0 ng/l (mean +/- SEM) vs. 135 +/- 15.1 ng/l, standing: 448 +/- 31.9 ng/l vs. 359 +/- 18.4 ng/l, walking: 388 +/- 22.5 ng/l vs. 234 +/- 22.1 ng/l). In EH chronic administration of prindolol led to a significant decrease in PNA concentrations under all the three test conditions to levels which did not differ significantly any more from those derived from NS. The adrenergic response to upright posture reflected in the percentage increase in PNA was significantly less in EH before prindolol when compared to the percentage increase in NS. On prindolol the adrenergic response was not abolidhed, yet it tended to approach the values found in NS. Before prindolol under resting conditions diastolic BP correlated closely with the corresponding PNA levels (p less than 0.01, r = 0.66, n = 15). This correlation could not be reestablished after prindolol treatment. The decrease in PNA after long-term treatment with prindolol was not correlated to the fall in blood pressure. The decrease in PNA indicates a lower activity of the sympathetic nervous system which may contribute to the antihypertensive effect of prindolol.

Effects of atenolol and hydrochlorothiazide on blood pressure and plasma catecholamines in essential hypertension.

“…In a series of "hyperadrenergic" hypertensives, metoprolol and propranolol reduced both the supine and erect plasma norepinephrine values. 8 A beta-adrenoceptor antagonist with intrinsic sympathomimetic activity, pindolol, has been reported 16 to lower plasma norepinephrine significantly in patients supine, erect, and post-exercise. Previous studies with atenolol have shown relatively consistent norepinephrine data with increases in supine and post-exercise values reported by Distler et al" and Winer et al 18 in hypertensive and normotensive subjects respectively.…”

Differences in psychic performance with guanfacine and clonidine in normotensive subjects.

“…Renzini, Brunori & Valori (1970) with modifications described by Brecht, Banthien & Schoeppe (1976). Forearm venous blood for the determination of plasma noradrenaline concentration was obtained under standardized conditions after each test session.…”

Sympathetic nervous system activity in patients with subarachnoid hemorrhage.

“…Of the 16, 5 patients received /?-blockers postoperatively and were excluded as their treatment with /8-blockers might have altered their plasma catecholamine concentrations. 24 Within 24 hours of admission informed consent was obtained from the patients and a venous blood sample was collected for plasma epinephrine, norepinephrine and D/3H measurements after 30 min of supine bed rest. In 14 patients a further sample (re-evaluation sample) was collected 2-12 hours either before they underwent neurosurgery or when they were deferred as unfit for surgery due to poor neurosurgical condition.…”