Renal water channel expression in newborns: Measurement of urinary excretion of aquaporin-2

Hirokazu Tsukahara, Ikue Hata, Kyoichi Sekine, Masakazu Miura, Fumikazu Kotsuji, Mitsufumi Mayumi

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Aquaporin-2 (AQP-2) encodes the vasopressin-regulated 'water channels' of the renal collecting duct and is excreted in human urine. We measured urinary excretion of AQP-2 by radioimmunoassay in 15 term and 10 preterm infants on day 1 and day 4 of life to determine the molecular basis of water balance during the newborn period. AQP-2 was detectable in the urine of term and preterm newborns, but AQP-2 excretion was severalfold less than the reported level in normal adults. Urinary excretion of AQP-2 significantly decreased postnatally, in parallel with a reduction in urine osmolality and arginine vasopressin (AVP) excretion. Urinary AQP-2 correlated positively and significantly with urine osmolality on days 1 and 4 and with AVP on day I in both groups. No significant differences were detected in AQP-2 levels between term and preterm newborns. Our findings suggest that vasopressin-regulated water channels are expressed in the renal collecting duct of both term and preterm newborns, although to a lesser extent as compared with adults, and these channels encoded by AQP-2 contribute to the urine concentrating power of the newborn kidney.

Original languageEnglish
Pages (from-to)1344-1347
Number of pages4
JournalMetabolism: Clinical and Experimental
Issue number11
Publication statusPublished - 1998
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology


Dive into the research topics of 'Renal water channel expression in newborns: Measurement of urinary excretion of aquaporin-2'. Together they form a unique fingerprint.

Cite this