Effect of beta‐adrenergic receptor blockade with propranolol on the response of plasma catecholamines and renin activity to upright tilting in normal subjects.

Abstract

1 Relationships between plasma catecholamines (measured as noradrenaline and adrenaline) and plasma renin activity (PRA) were examined at rest and during passive head-up tilting for 30 min in nine normal subjects, before and after treatment with propranolol 160 mg daily for 7 days. 2 Noradrenaline (NA) and adrenaline (A) increased substantially after tilting for 15 min. There were no changes in PRA. After 30 min tilting, NA remained elevated, whereas A had returned to resting levels. A significant increase in PRA was apparent at 30 min. Pulse rate and diastolic blood pressure increased progressively during tilting. Systolic pressure did not change. 3 Treatment with propranolol reduced pulse rate and systolic blood pressure at rest and during tilting. Resting catecholamine concentrations and the response of NA to tilting were unaffected. In contrast, treatment prolonged the A response leading to significantly higher levels after 30 min tilting. Propranolol reduced PRA in six of the nine subjects and prevented the increase with tilting observed before treatment.

How intrinsic sympathomimetic activity modulates the haemodynamic responses to beta‐adrenoceptor antagonists. A clue to the nature of their antihypertensive mechanism.

“…Opinions are divided concerning the role of this mechanism in the decrease of vascular resistance that initiates the hypotensive effect of i-adrenoceptor blockers. An important argument against this possibility has always been that during long-term treatment with ladrenoceptor blockers plasma noradrenaline increases as a rule (Hansson & Hokfelt, 1975;Distler et al, 1978;De Leeuw et al, 1977;Morganti et al, 1978;Rahn etal., 1978;Lijnen etal., 1979;Franz et al, 1980;Man in 't Veld et al, 1980;Esler et al, 1981;Vandongen et al, 1981), (Table 2).…”

Β‐adrenoceptors in the Hypertrophied Right Ventricle of the Dog With Pulmonary Stenosis

“…Prior to determination, the tissue samples were thawed and homogenized in 10 volumes of 100 mmol/l perchloric acid containing 5 mmol/l glutathione. The homogenates were centrifuged at 10 OOO g for 10 min and the catecholamine content of the supernatant and of plasma was measured by the radioenzymatic method of Peuler & Johnson (1977) as modified by Vandongen et al (1981).…”

The effect of posture on the sympathoadrenal response to theophylline infusion.

“…This concept is supported by the demonstration of potentiation, by theophylline, of the rise in plasma cyclic AMP seen following inhalation of small doses of isoprenaline, although theophylline given alone caused no rise in plasma cyclic AMP (Trembath & Shaw, 1978). We therefore measured the plasma cyclic AMP response to theophylline infusion in normal subjects when supine and erect, since the erect posture is a stimulus to the sympathetic system (Vandongen et al, 1981).…”