Physiological increases in circulating noradrenaline are antinatriuretic in man.

Low-dose (0.025 micrograms/kg per min) noradrenaline infusion, resulting in a physiological plasma increment (280 pg/ml), was antinatriuretic in normal salt-replete male subjects. The reduction in sodium excretion (-20%, P less than 0.01) occurred without any change in the glomerular filtration rate but was associated with a significant (P less than 0.02) decline in lithium clearance. These results suggest that changes in circulating noradrenaline, within the physiological range, can decrease sodium excretion in man by enhancing proximal tubular sodium reabsorption. These findings extend previous investigations in man which used pharmacological doses of noradrenaline and are in agreement with animal evidence for a renal tubular antinatriuretic effect of the sympathetic nervous system.