Oxprenolol and the circulation during anaesthesia in the dog: Influence of intrinsic sympathomimetic activity

Abstract

Oxprenolol is a non-selective adrenergic beta-receptor antagonist displaying beta-mimetic activity. To test the hypothesis that beta-mimetic activity could minimize the response of the circulation to adrenergic beta-receptor blockade, cumulative dose-response curves to oxprenolol 0.1-1.6mgkg-1 were obtained in seven anaesthetized dogs. Anaesthesia was maintained with 0.5% halothane supplementing nitrous oxide 66% in oxygen, under moderately hypocapnic IPPV. Oxprenolol, up to 0.4mgkg-1 i.v., caused modest increases in heart rate, LVdP/dt max and cardiac output. With the largest dose (1.6mg kg-1), significant increases in heart rate(+19%), LVdP/dtmax(+13%)and cardiac output(+27%)were observed while arterial pressure remained unchanged and systemic vascular resistance decreased (-18%). © 1981 Macmillan Publishers Ltd.