Microneurography: a technique for assessing central neural effects of adrenergic drugs on sympathetic outflow in humans

Abstract

Alpha-2 receptor agonists may act to decrease sympathetic influences through central neural actions that inhibit sympathetic outflow and peripheral adrenergic effects that inhibit release of norepinephrine. Direct intraneural recordings using microneurography of postganglionic sympathetic nerve activity in humans permit assessment of effects of alpha-2 agonists on central sympathetic outflow. Microneurographic studies during administration of clonidine suggest that alpha-2 agonists produce a dose-related modulation of central sympathetic nerve discharge, but that other mechanisms presumably involving stimulation of inhibitory peripheral presynaptic alpha-2 receptors are also involved in the antihypertensive action of these agents. This suggests that alpha-2 agonists exert combined central and peripheral effects on sympathetic influences in humans.