The Role of the Sympathetic Nervous system in the Modulation of Sodium Excretion

Abstract

To investigate the existence of opposing renal noradrenergic and dopaminergic modulation of renal sodium excretion, urinary excretion rates of NE, DA and DOPAC were measured in different states of sodium balance. A natriuretic index, DOPAC/NE, was found to correlate closely with the state of sodium balance in normal men subjected to very low (10 mEq/d) or very high (800 mEq/d) sodium intake. Additional studies utilizing rapid sodium and volume expansion and contraction confirmed the utility of this natriuretic index. Hypertensive men demonstrated significantly lower values for this index than did normotensive subjects under similar study conditions. These studies provide new evidence of abnormalities in the adrenergic-dopaminergic system in human hypertension and support a link between these systems and renal sodium handling.