title: Regulation of the basolateral chloride/base exchangers AE1 and SLC26A7 in the kidney collecting duct in potassium depletion.
abstract: 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 approximately 500% in the cortex and approximately 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.
authors.affiliation: Department of Medicine, University of Cincinnati, 231 Albert Sabin Way, MSB G259, Cincinnati, OH 45267-0585, USA.
authors.forename: Sharon
authors.initials: S
authors.lastname: Barone
authors.forename: Hassane
authors.initials: H
authors.lastname: Amlal
authors.forename: Minna
authors.initials: M
authors.lastname: Kujala
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Fiona
authors.initials: F
authors.lastname: Karet
authors.forename: Ann
authors.initials: A
authors.lastname: Blanchard
authors.forename: Juha
authors.initials: J
authors.lastname: Kere
authors.forename: Manoocher
authors.initials: M
authors.lastname: Soleimani
mesh_terms: D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000502:physiology*; D017920:Antiporters / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000502:physiology*; D008297:Male; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000076988:Sulfate Transporters