EFFECT OF EXTREME PREMATURITY ON RENAL DOPAMINE AND NOREPINEPHRINE EXCRETION DURING THE NEONATAL-PERIOD

Dopamine (DA), produced in proximal tubular cells, is believed to be a n important intrarenal natriuretic hormone, Experimental studies have shown that the natriuretic effect of DA is less pronounced in the feta l kidney. We have evaluated renal DA and norepinephrine (NE) in the ne onatal period, using urinary excretion as an indicator of renally prod uced/released catecholamines, In very low-birth-weight infants (25-30 weeks gestational age) there was an increase in urinary DA (pmol/mu mo l urinary creatinine) and NE (pmol/mu mol urinary creatinine) from 1 t o 13 days postnatal age, despite a decrease in sodium excretion. Urina ry NE correlated with plasma NE, whereas plasma DA was undetectable. I n summary, NE excretion parallels plasma levels and could reflect the general sympathoadrenal activity, whereas DA is primarily of renal ori gin. Renal DA and NE increase in the first 2 weeks of life in immature infants. We conclude that the catecholamine system of the human kidne y undergoes maturational changes postnatally.