The urinary activity of angiotensin-converting enzyme in preterm, full-term newborns, and children.
The urinary activity of the angiotensin-converting enzyme (U(ACE)) is not yet completely documented in human neonates. We measured the U(ACE) in 36 premature neonates on the 1st day and in the 1st, 2nd, 3rd, and 4th weeks of life, in 22 full-term neonates between the 1st and 2nd days, and in 30 nursing and preschool children between 1 month and 6 years of age. The urinary excretion of sodium (U(Na)/U(Cr)) and the potassium/sodium index (U(K)/U(Na)) were analyzed in the neonates. U(ACE) was greater in premature than in full-term neonates and greater in both than in older children (p<0.001). In the premature neonates, U(ACE) peaked at the 2nd week, the U(Na)/U(Cr) index decreased, and the U(K)/U(Na) index increased between the 1st day and the 2nd week (p<0.001). The U(Na)/U(Cr) index on the 1st day and in the 1st and 2nd weeks was greater in premature than in full-term neonates (p<0.001). There was no significant correlation between the U(ACE) and the U(Na)/U(Cr) index. In conclusion, the U(ACE) profile was shown to be age dependent and related to the postnatal renal development. The increase in U(ACE) activity may reflect the high activity of the neonatal intrarenal renin-angiotensin system (RAS).
Lopes Del Ben
Graziela
G
Pediatric Nephrology Division, Department of Pediatrics, Paulista Medical School, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil. gdelben@uol.com.br
Redublo Quinto
Beata Marie
BM
Casarini
Dulce Elena
DE
Bueno Ferreira
Luiz Carlos
LC
Sousa Ayres
Sérgio
S
de Abreu Carvalhaes
João Tomás
JT
D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000652:urine*; D011446:Prospective Studies; D012084:Renin-Angiotensin System / Q000502:physiology; D047929:Term Birth
D007703:Peptidyl-Dipeptidase A