title: Dietary Cl(-) restriction upregulates pendrin expression within the apical plasma membrane of type B intercalated cells.
abstract: Pendrin, encoded by Slc26a4, is a Cl(-)/HCO(3)(-) exchanger expressed in the apical region of type B and non-A, non-B intercalated cells, which regulates renal NaCl excretion. Dietary Cl(-) restriction upregulates total pendrin protein expression. Whether the subcellular expression of pendrin and whether the apparent vascular volume contraction observed in Slc26a4 null mice are Cl(-) dependent, but Na(+) independent, is unknown. Thus the subcellular distribution of pendrin and its role in acid-base and fluid balance were explored using immunogold cytochemistry and balance studies of mice ingesting a NaCl-replete or a Na(+)-replete, Cl(-)-restricted diet, achieved through substitution of NaCl with NaHCO(3). Boundary length and apical plasma membrane pendrin label density each increased by approximately 60-70% in type B intercalated cells, but not in non-A, non-B cells, whereas cytoplasmic pendrin immunolabel increased approximately 60% in non-A, non-B intercalated cells, but not in type B cells. Following either NaCl restriction or Cl(-) restriction alone, Slc26a4 null mice excreted more Cl(-) and had a higher arterial pH than pair-fed wild-type mice. In conclusion, 1) following dietary Cl(-) restriction, apical plasma membrane pendrin immunolabel increases in type B intercalated cells, but not in non-A, non-B intercalated cells; and 2) pendrin participates in the regulation of renal Cl(-) excretion and arterial pH during dietary Cl(-) restriction.
authors: Department of Medicine, University of Florida College of Medicine, Gainesville, Florida, USA.
authors: Jill W
authors: JW
authors: Verlander
authors: Young Hee
authors: YH
authors: Kim
authors: Wonkyong
authors: W
authors: Shin
authors: Truyen Derek
authors: TD
authors: Pham
authors: Kathryn A
authors: KA
authors: Hassell
authors: William H
authors: WH
authors: Beierwaltes
authors: Eric D
authors: ED
authors: Green
authors: Lorraine
authors: L
authors: Everett
authors: Sharon W
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authors: Matthews
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