title: Direct 24-hour haemodynamic monitoring after starting beta-blocker therapy: studies with pindolol in hypertension.
abstract: The acute haemodynamic effects of the non-selective beta-adrenoceptor antiagonist pindolol which has considerable intrinsic sympathomimetic activity (ISA), were studied in 10 patients with essential hypertension for 24 h. One hour after oral dosing (10 mg), the drug reduced supine arterial pressure significantly. The maximum antihypertensive effect was observed after 3-4 h (-15 +/- 3%, P less than 0.001). The fall in arterial pressure was associated with a 25% reduction of systemic vascular resistance (P less than 0.001) after 24 h. By that time cardiac output was increased by 16 +/- 5% (P less than 0.05). Cardiac filling pressures and pulmonary artery pressure did not change. The vasodilator effect of pindolol cannot easily be explained by suppression of plasma renin activity since changes in arterial pressure and plasma renin were inversely correlated (r = -0.58, P less than 0.001). Despite the antihypertensive and vasodilator effect of pendolol, plasma noradrenaline did not rise. The rapid fall in arterial pressure and systemic vascular resistance may be explained by the absence of an initial reflex vasoconstriction which normally follows blockade of cardiac beta-receptors. This may be related to ISA on cardiac and vascular postsynaptic beta-receptors. Concomitant blockade of central and/or peripheral presynaptic beta-receptors is suggested by the absence of a rise in plasma noradrenaline and may contribute to the vasodilator action of pindolol.
mesh_terms: D000293:Adolescent; D000328:Adult; D004341:Drug Evaluation; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010869:Pindolol / Q000627:therapeutic use*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D013997:Time Factors
chemical_list: D011943:Receptors, Adrenergic, beta; D010869:Pindolol