Oxprenolol

Like other beta-adrenergic antagonists, oxprenolol competes with adrenergic neurotransmitters such as catecholamines for binding at sympathetic receptor sites. Like propranolol and timolol, oxprenolol binds at beta(1)-adrenergic receptors in the heart and vascular smooth muscle, inhibiting the effects of the catecholamines epinephrine and norepinephrine and decreasing heart rate, cardiac output, and systolic and diastolic blood pressure. It also blocks beta-2 adrenergic receptors located in bronchiole smooth muscle, causing vasoconstriction. By binding beta-2 receptors in the juxtaglomerular apparatus, oxprenolol inhibits the production of renin, thereby inhibiting angiotensin II and aldosterone production. Oxprenolol therefore inhibits the vasoconstriction and water retention due to angiotensin II and aldosterone, respectively.