Baroreceptors and hypertension.

D espite considerable research, the role played by the sympathetic nervous system in the pathogenesis of essential hypertension remains poorly understood.' In virtually all forms of chronic hypertension, the principal hemodynamic fault is an elevation in systemic vascular resistance.' Because sympathetic vasomotor outflow normally is under tonic reflex restraint by sinoaortic and cardiopulmonary baroreceptors,2 impairments in this baroreflex restraint are hypothesized to play a permissive role in the pathogenesis of essential hypertension.1-3 The important study by Rea and Hamdan4 in this issue of Circulation sheds new light on this hypothesis.