Effect of Beta-Adrenergic Blockade on Plasma Volume in Human Subjects

Variations in the sympathetic tone are known to induce changes in plasma volume. Infusion of catecholamines decreases the plasma volume (1, 2). Some patients with pheochromocytoma show subnormal values of plasma volume (3). Increased sympathetic activity after hypoxia is associated with a reduction of plasma volume (4).During the course of an investigation on plasma volume in borderline hypertension (5) we encountered data related to the role of the sympathetic nervous system in the regulation of plasma volume. Plasma volume was measured before and after beta-adrenergic blockade with propranolol. In order to better understand observed changes in plasma volume an attempt is made to separate the effect of beta blockade on cardiac output, peripheral resistance and central venous pressure from its other hemodynamic effects.Materials and Methods. Twenty-seven males from 18 to 26 years of age were studied. Fourteen subjects had borderline hypertension, i.e., at least one diastolic above and one below 90 out of ...