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- Title
Role of ion exchangers in mediating NaCl transport in the proximal tubule.
- Authors
Aronson, Peter S.; Aronson, P S
- 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.
- Subjects
ION exchange (Chemistry); SALT; BIOLOGICAL transport; KIDNEY tubules; ANIONS; GLUCOCORTICOIDS; ACIDOSIS; ANIMAL experimentation; COMPARATIVE studies; RESEARCH methodology; MEDICAL cooperation; RESEARCH; EVALUATION research
- Publication
Kidney International, 1996, Vol 49, Issue 6, p1665
- ISSN
0085-2538
- Publication type
journal article
- DOI
10.1038/ki.1996.243