The sympathoadrenal and renin-angiotensin system (RAS) activity at birth was evaluated in three groups of full term neonates; neonates born after elective caesarean section (Grp 1) following uncomplicated vaginal delivery(Grp 2) and neonates with hypoxic-ischemic encephalopathy (HIE)(Grp 3). Mean values of catecholamines, plasma renin activity (PRA), and aldosterone were normal in neonates following elective caesarean section with no labor, elevated in neonates born after vaginal delivery and exaggerated in neonates with HIE. In all 5 measurements, Grp 2 vs Grp 1, p<.05, Grp 3 vs Grp 1 and Grp 3 vs Grp 2, p<.05. See table below.

Table 1 No caption available.
Full size table

In a double blind prospective study half of the HIE neonates were treated with IV dopamine (2.5ngm/kg/min) and the other half with placebo dextrose in water. The mean fall of PRA on the 10th postnatal day in the dopamine and placebo groups was 32ngm/ml/hr and 7ngm/ml respectively (p=0.001) and the fall in aldosterone levels was 329pgm/ml and 1031pgm/ml respectively (p<.01). In the dopamine treated group, 1 infant died and 2 infants had mild neurological deficits on follow-up while there were 3 deaths and 6 infants with major neurological deficits in the placebo group. We conclude that immediate and late outcome following HIE improves following administration of dopamine. We speculate this is due to the normalization of PRA and aldosterone levels which are markers of circulating angiotensin II, a known potent vasoconstrictor and excitatory neurotransmitor. Dopamine may open receptor-operated calcium channels liberating cytosolic calcium and activating the cerebral RAS which has a pathogenic role in HIE. (Values represent mean±SD)

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account
Continue with Google
Continue with ORCiD