Neurovascular mechanisms and sodium balance in the pathogenesis of hypertension. Physiological studies have clarified the role that the brain has in the interplay between salt balance and hypertension. Neural mechanisms and endocrine secretions play a pivotal role in the adaptation of mammals to changes in the intake and excretion of sodium. Maneuvers that alter the concentration of sodium in the plasma modify the sensitivity of baroreceptor reflexes and alter vascular reactivity. These changes may be mediated in part by the release of vasopressin. The research also suggests that the brain indirectly modulates the ability of the vascular endothelium to release vasoactive factors. Collectively, these studies illustrate the multiple effects of the sodium ion on the peripheral neural and central endocrine mechanisms that participate in the regulation of arterial pressure. 