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SLC26A7: a basolateral Cl-/HCO3- exchanger specific to intercalated cells of the outer medullary collecting duct

SLC26A7: a basolateral Cl-/HCO3- exchanger specific to intercalated cells of the outer medullary... The outer medullary collecting duct (OMCD) plays an important role in bicarbonate reabsorption and acid-base regulation. An apical V-type H + -ATPase and a basolateral exchanger, located in intercalated cells of OMCD, mediate the bicarbonate reabsorption. Here we report the identification of a new basolateral exchanger in OMCD intercalated cells in rat kidney. Northern hybridizations demonstrated the predominant expression of this transporter, also known as SLC26A7, in the outer medulla, with lower expression levels in the inner medulla. SLC26A7 was recognized as a ∼90-kDa band in the outer medulla by immunoblot analysis and was localized on the basolateral membrane of a subset of OMCD cells by immunocytochemical staining. No labeling was detected in the cortex. Double-immunofluorescence labeling with the aquaporin-2 and SLC26A7 antibodies or anion exchanger-1 and SLC26A7 antibodies identified the SLC26A7-expressing cells as α-intercalated cells. Functional studies in oocytes demonstrated that increasing the osmolality of the media (to simulate the physiological milieu in the medulla) increased the exchanger activity mediated via SLC26A7 by about threefold ( P < 0.02 vs. normal condition). We propose that SLC26A7 is a basolateral exchanger in intercalated cells of the OMCD and may play an important role in bicarbonate reabsorption in medullary collecting duct. anion exchanger; basolateral membrane; aquaporin-2 Address for reprint requests and other correspondence: M. Soleimani, Division of Nephrology and Hypertension, Dept. of Medicine, Univ. of Cincinnati, 231 Albert Sabin Way, MSB G259, Cincinnati, OH 45267-0585 (E-mail: Manoocher.Soleimani@uc.edu ). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Renal Physiology The American Physiological Society

SLC26A7: a basolateral Cl-/HCO3- exchanger specific to intercalated cells of the outer medullary collecting duct

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References (42)

Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0363-6127
eISSN
1522-1466
DOI
10.1152/ajprenal.00219.2003
pmid
12965893
Publisher site
See Article on Publisher Site

Abstract

The outer medullary collecting duct (OMCD) plays an important role in bicarbonate reabsorption and acid-base regulation. An apical V-type H + -ATPase and a basolateral exchanger, located in intercalated cells of OMCD, mediate the bicarbonate reabsorption. Here we report the identification of a new basolateral exchanger in OMCD intercalated cells in rat kidney. Northern hybridizations demonstrated the predominant expression of this transporter, also known as SLC26A7, in the outer medulla, with lower expression levels in the inner medulla. SLC26A7 was recognized as a ∼90-kDa band in the outer medulla by immunoblot analysis and was localized on the basolateral membrane of a subset of OMCD cells by immunocytochemical staining. No labeling was detected in the cortex. Double-immunofluorescence labeling with the aquaporin-2 and SLC26A7 antibodies or anion exchanger-1 and SLC26A7 antibodies identified the SLC26A7-expressing cells as α-intercalated cells. Functional studies in oocytes demonstrated that increasing the osmolality of the media (to simulate the physiological milieu in the medulla) increased the exchanger activity mediated via SLC26A7 by about threefold ( P < 0.02 vs. normal condition). We propose that SLC26A7 is a basolateral exchanger in intercalated cells of the OMCD and may play an important role in bicarbonate reabsorption in medullary collecting duct. anion exchanger; basolateral membrane; aquaporin-2 Address for reprint requests and other correspondence: M. Soleimani, Division of Nephrology and Hypertension, Dept. of Medicine, Univ. of Cincinnati, 231 Albert Sabin Way, MSB G259, Cincinnati, OH 45267-0585 (E-mail: Manoocher.Soleimani@uc.edu ).

Journal

AJP - Renal Physiology – The American Physiological Society

Published: Jan 1, 2004

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