Central hypotensive effect of propranolol.

Propranolol is an antihypertensive drug whose mode of action in lowering arterial pressure remains undecided. Animal experiments indicate that an action within the central nervous system (CNS) contributes to the hypotensive effect. Intravenous infusion of propranolol to the conscious rabbit lowers arterial pressure and this is accompanied by a decrease in preganglionic sympathetic nervous activity. This indicates that propranolol decreases sympathetic nervous outflow by a central action and since the dextro isomer of propranolol does not exert such an effect then this action must be related to beta-adrenoceptor blockade.