Journal Article

Regulation of the basolateral chloride/base exchangers AE1 and SLC26A7 in the kidney collecting duct in potassium depletion

Sharon Barone, Hassane Amlal, Minna Kujala, Jie Xu, Fiona Karet, Ann Blanchard, Juha Kere and Manoocher Soleimani

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 22, issue 12, pages 3462-3470
Published in print December 2007 | ISSN: 0931-0509
Published online September 2007 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfm486
Regulation of the basolateral chloride/base exchangers AE1 and SLC26A7 in the kidney collecting duct in potassium depletion

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In the present study, the effect of potassium depletion on the expression of acid-base transporters in the collecting duct was examined. Toward this end rats were fed a potassium-free diet for 3 weeks. Thereafter, the expression of the basolateral chloride/bicarbonate exchangers AE1 and SLC26A7 and the apical H+-ATPase was examined by northern hybridization, immunoblot analysis and immunofluorescence labelling. The mRNA expression of AE1 increased by a robust ∼500% in the cortex and ∼70% in the outer medulla, which translated into a huge increase in AE1 protein abundance in the cortex and a moderate increase in the outer medulla in K-depletion. The mRNA expression of SLC26A7 did not change significantly but its protein abundance showed a robust increase in the outer medulla. The expression of SLC26A7 remained undetected in the cortex in K-depleted rats. The post translational increase in SLC26A7 membrane abundance in potassium depletion was recapitulated in vitro using epitope-tagged SLC26A7. H+-ATPase displayed enhanced apical plasma membrane immunoreactivity in the OMCD in K-depletion. We suggest that the up-regulation of SLC26A7 and AE1 on the basolateral membrane of A-intercalated cells in the OMCD and CCD, respectively, along with H+-ATPase on the apical membrane, contributes to enhanced bicarbonate absorption in the collecting duct in K-depletion.

Keywords: bicarbonate absorption; kidney tubules; metabolic alkalosis

Journal Article.  4144 words.  Illustrated.

Subjects: Nephrology

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