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Detection of NHE3 and NCC in urine as biomarkers of renal function in extremely premature neonates
Author(s) -
Swan Kathleen Beutler,
Homsy Yves,
Frokiaer Jorgen
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb127-c
Subject(s) - urine , cotransporter , urinary system , kidney , urine sodium , chemistry , sodium , renal function , medicine , transporter , endocrinology , antibody , lipocalin , biochemistry , immunology , organic chemistry , gene
Hydronephrosis associated with neonatal ureter obstruction (NUO) is a common cause of renal failure in children. Medical management of these individuals is complicated by the lack of precise tools to assess early changes in kidney function associated with NUO. Urinary biomarkers may serve as indicators of early kidney changes. We isolated renal sodium transporter protein from the urine of neonates. Urine samples (1 ml to 36 ml) were obtained from 33 neonates, born at gestational ages between 24–40 weeks. Samples were preserved with protease inhibitors, then subjected to ultracentrifugation to isolate sodium transporter proteins present in low‐density membrane fractions. Immunoblots were probed with rabbit antibodies raised to rat type 3 Na‐H exchanger (NHE3) of the proximal tubule, and the Na‐Cl cotransporter (NCC) of the distal convoluted tubule. Each of these sodium transporters was detectable in the low‐density exosomal fraction of urine. Antibody to NHE3 labeled a defined band at an approximate MW of 85 KD; NCC antibody labeled a low molecular weight protein. In addition, each antibody labeled specific high molecular weight proteins, consistent with sodium transporters existing as complexes in low‐density exosomal vesicles in urine. Further investigation is indicated to determine the change in urinary sodium transporter abundance with maturation of the kidney and in response to NUO.