The role of endogenous dopamine (DA) in regulating arginine vasopressin (AVP) release and renal water excretion was studied in 10 premature infants with a mean birth weight of 1,341 g (range 1,150-1,660 g) and a mean gestational age of 30.2 weeks (28-33 weeks), who were given metoclopramide (MTC), a specific DA antagonist. It was demonstrated that in response to MTC urine flow rate increased significantly from a basal value of 0.90 ± 0.07 to 1.27 ± 0.09 ml/min/1.73 m2 (mean ± SE; p < 0.01), urinary sodium excretion from 6.10 ± 1.47 to 11.7 ± 2.24 μEq/min/1.73 m2 (p < 0.025) and osmolar clearance from 0.38 ± 0.044 to 0.600 ± 0.075 ± 0.075 ml/min/1.73 m2 (p < 0.01). MTC administration did not cause any alterations in free water clearance, whereas urinary AVP excretion fell significantly from 49.38 ± 10.13 to 32.66 ± 6.53 ng/min/1.73 m2 (p < 0.05) after MTC. It is concluded that, contrary to adults, in low birth weight premature infants endogenous DA is enhancing rather than inhibitng AVP release and the MTC-induced water diuresis is independent of the fall of AVP since free water clearance remained unaltered after MTC.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Developmental Biology