Developmental changes in proximal tubule NaCl transport

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The proximal tubule reabsorbs two thirds of the filtered NaCl in an isoosmotic fashion. In the adult proximal tubule, active NaCl transport is mediated by the parallel operation of Na+/H+ and Cl-/base exchangers, and a substantive amount of chloride transport occurs passively across the paracellular pathway. Studies in the neonatal proximal tubule have resulted in unexpected results. The isoform of the Na+/H+ exchanger mediating proximal tubule sodium absorption, NHE3, is virtually absent in the neonatal rat kidney. NHE8, an isoform of the Na+/H+ exchange, in low abundance on the apical membrane of the adult proximal tubule, is present in high abundance in the neonatal segment. Whereas chloride permeability is high in the adult, favoring passive paracellular chloride flux, the neonatal proximal tubule is virtually impermeable to chloride ions. This is again due to a developmental change in isoforms of proteins forming the tight junction. The permeability properties of epithelia are due to a family of tight junction proteins called claudins. Claudins 6 and 9 are expressed in the neonatal proximal tubule at a time when chloride permeability is low, but these claudin isoforms are virtually absent in the adult segment. The causes for these postnatal changes in proximal tubular transport and developmental isoform changes are also discussed in this review.

Original languageEnglish (US)
Pages (from-to)185-194
Number of pages10
JournalPediatric Nephrology
Volume23
Issue number2
DOIs
StatePublished - Feb 2008

Fingerprint

Chlorides
Protein Isoforms
Claudins
Tight Junction Proteins
Permeability
Sodium-Hydrogen Antiporter
Active Biological Transport
Epithelium
Sodium
Ions
Kidney
Membranes

Keywords

  • Acidification
  • NHE3
  • NHE8
  • Permeability

ASJC Scopus subject areas

  • Nephrology
  • Pediatrics, Perinatology, and Child Health

Cite this

Developmental changes in proximal tubule NaCl transport. / Baum, Michel.

In: Pediatric Nephrology, Vol. 23, No. 2, 02.2008, p. 185-194.

Research output: Contribution to journalArticle

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