Role of ion exchangers in mediating NaCl transport in the proximal tubule

Kidney Int. 1996 Jun;49(6):1665-70. doi: 10.1038/ki.1996.243.

Abstract

The reabsorption of NaCl in the proximal tubule occurs passively through the paracellular pathway, and actively by a transcellular route. Transcellular NaCl transport involves Na(+)-coupled Cl- entry across the apical membrane by two mechanisms involving Cl(-)-organic anion exchange. One mechanism is Cl(-)-formate exchange with recycling of formate from lumen to cell by H(+)-coupled formate transport in parallel with Na(+)-H+ exchange. A second mechanism is Cl(-)-oxalate exchange with recycling of oxalate from lumen to cell by oxalate-sulfate exchange in parallel with Na(+)-sulfate cotransport. Cl- exit across the basolateral membrane is most likely mediated by Cl- channels. Apical membrane Na(+)-H+ exchange is involved in mediating both NaHCO3 and NaCl reabsorption in the proximal tubule. Immunocytochemical studies indicate that NHE3 is the principal Na(+)-H+ exchanger isoform expressed on the brush border membrane. Detection of NHE3 in a subapical, intracellular, vesicular compartment in proximal tubule cells is consistent with its possible regulation by membrane trafficking. That NHE3 is the isoform responsible for apical membrane Na(+)-H+ exchange activity is supported by studies of inhibitor sensitivity, and by studies demonstrating increased expression of NHE3 protein in association with enhanced Na(+)-H+ exchange activity during renal maturation and in response to glucocorticoids and metabolic acidosis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Ion Transport / physiology
  • Kidney Tubules, Proximal / chemistry
  • Kidney Tubules, Proximal / metabolism*
  • Sodium Chloride / metabolism*

Substances

  • Sodium Chloride