Effect of low-dose dopamine infusion on urinary prostaglandin E2 excretion in sick, preterm infants

Abstract

In pharmacological doses dopamine (DA) will interact with several endocrine systems and both inhibit (prolactin, thyrotropin) and enhance (renin, angiotensin) hormonal release. In this study we have examined whether DA given to preterm neonates will influence prostaglandin (PG) production. The question is of importance since vasodilator PGs play a role in postnatal adaptation. We determined the effect of low dose DA infusion on the 24 h urinary PGE2 excretion rate (an index of renal PGE2 synthesis) in preterm infants. Six preterm neonates, with a 24-h requirement of 2 micrograms/kg per min DA treatment for oedema, moderate oliguria, poor peripheral perfusion and/or mild systemic hypotension were studied on days 2 (Day 1), 3 (Day 2, the day of DA infusion), and 4 (Day 3, DA discontinued) of life. Six preterm infants (control group) that did not require DA infusion were also studied to monitor possible spontaneous changes in the renal PGE2 production on days 2, 3 and 4 of life. In the control group urine output (Uv) and PGE2 excretion rate remained unchanged during the study. In the study group DA administration resulted in nearly two-fold increases in both the Uv (194%) and PGE2 excretion (182%). Urinary PGE2 excretion was, however, closely related to urine flow in both the control infants (Day 1-3) and the study group infants (Day 1-2). Since increased diuresis stimulates renal PGE2 production, our data suggest that the increased PGE2 excretion on Day 2 in the study group was not due to a direct effect of DA on PGE2 synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Low-Dose Dopamine Infusion on Cardiovascular and Renal Functions, Cerebral Blood Flow, and Plasma Catecholamine Levels in Sick Preterm Neonates

“…Thus, while maintaining blood pressure and GFR comparable to those in untreated, normotensive controls, 2 pglkglmin dopamine induces maximum diuresis and natriuresis in the I-d-old mildly hypotensive preterm neonate. Therefore, these findings support our previous observations (24,32,33) and demonstrate that the dopamineinduced diuresis and natriuresis also result from the direct tubular effects of the drug.…”

“…In children and adults, dopamine, in increasing concentrations, activates the dopaminergic, then the 8-adrenergic, and finally the a-adrenergic recep tors (10). The present findings and our earlier observations (3,8,32,33) as well as those reported by others (2,34) suggest that the order of receptor sensitivity is different in the preterm infant, i.e. clinical signs of stimulation of the a-adrenoreceptors and dopamine receptors occur before those of the 8-adrenoreceptors.…”

“…Our earlier studies provided indirect evidence for the existence of the direct tubular actions of dopamine in the 14-old preterm human neonate (24,32,33). The present findings demonstrate that 2 and 4 pg/kg/min dopamine induce significant but similar increases in UV and sodium excretion in this age group, whereas the higher dose of the drug also results in statistically significant elevations in blood pressure and C, .…”

Cardiovascular Drug Therapy for Human Newborn: Review of Pharmacodynamic Data

“…Low dose dopamine received wide acceptance among neonatologists as treatment for low urine output. However there is only one RCT assessing renal effects of dopamine published in 1988 which showed that 2 mcg/kg/min dopamine increased urine output significantly compared to controls [28]. In normotensive oliguric preterm newborns 2.5 mcg/kg/min dopamine infusion increased urine output and the same effect was observed in sick newborns with 2 mcg/kg/min dose [29,30].…”