Effects of Dietary Sodium and of Acute Saline Infusion on the Interrelationship between Dopamine Excretion and Adrenergic Activity in Man

A B S T R A C T The effects of dietary sodium and of saline infusion on urinary dopamine and norepinephrine and on the relationship of these catecholamines to ad- renergic activity were determined. In seven normal subjects on a 9-meq sodium intake, urinary dopamine and norepinephrine were 13618 (SE) and 37.45.3 Ag/day, respectively. When sodium intake was increased to 209 or 259 meq/day, urinary dopamine increased to 19520 Ag/day (P < 0.01) whereas urinary norepi- nephrine decreased to 21.13.0 Ag/day (P < 0.01). In- fusion of saline in seven subjects increased sodium ex- cretion and urinary dopamine (from 2.180.22 to 2.72 0.19 jg/20 min, P < 0.01), but decreased plasma dop- amine-fl-hydroxylase by 33% and urinary norepineph- rine insignificantly. The clearance of inulin and p- aminohippurate did not change significantly and filtra- tion fraction was the same. The data indicate that an increase in dietary sodium or infusion of saline results in an apparent decrease in adrenergic activity and an increase in urinary dopamine. Dopamine excretion would thus appear to relate inversely to adrenergic activity and to parallel sodium excretion. These findings suggest a possible role for dopamine and norepinephrine in the regulation of renal sodium excretion.