Deletion of Slc26a6 alters the stoichiometry of apical Cl-/HCO3 - exchange in mouse pancreatic duct

Hiroshi Ishiguro, Ying Song, Akiko Yamamoto, Martin C. Steward, Shigeru Ko, Andrew K. Stewart, Manoocher Soleimani, Bai Chun Liu, Takaharu Kondo, Chun Xiang Jin

Research output: Contribution to journalArticle

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Abstract

To define the stoichiometry and molecular identity of the Cl-/HCO3 - exchanger in the apical membrane of pancreatic duct cells, changes in luminal pH and volume were measured simultaneously in interlobular pancreatic ducts isolated from wild-type and Slc26a6-null mice. Transepithelial fluxes of HCO3 - and Cl- were measured in the presence of anion gradients favoring rapid exchange of intracellular HCO3 - with luminal Cl- in cAMP-stimulated ducts. The flux ratio of Cl- absorption/ HCO3 - secretion was ~0.7 in wild-type ducts and ~1.4 in Slc26a6-/- ducts where a different Cl-/HCO3 - exchanger, most likely SLC26A3, was found to be active. Interactions between Cl-/HCO3 - exchange and cystic fibrosis transmembrane conductance regulator (CFTR) in cAMP-stimu-lated ducts were examined by measuring the recovery of intracellular pH after alkali-loading by acetate prepulse. Hyperpolarization induced by luminal application of CFTRinh-172 enhanced HCO3 - efflux across the apical membrane via SLC26A6 in wild-type ducts but significantly reduced HCO3 - efflux in Slc26a6-/- ducts. In microper-fused wild-type ducts, removal of luminal Cl-, or luminal application of dihydro-4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid to inhibit SLC26A6, caused membrane hyperpolarization, which was abolished in Slc26a6-/- ducts. In conclusion, we have demonstrated that deletion of Slc26a6 alters the apparent stoichiometry of apical Cl-/ HCO3 exchange in native pancreatic duct. Our results are consistent with SLC26A6 mediating 1:2 Cl-/HCO3 - exchange, and the exchanger upregulated in its absence, most probably SLC26A3, mediating 2:1 exchange.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume303
Issue number8
DOIs
Publication statusPublished - 2012 Oct 15

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Chloride-Bicarbonate Antiporters
Pancreatic Ducts
Membranes
Cystic Fibrosis Transmembrane Conductance Regulator
Alkalies
Anions
Acetates
Acids

Keywords

  • Isolated pancreatic duct
  • Microperfusion
  • Micropuncture
  • Stoichiometry

ASJC Scopus subject areas

  • Cell Biology
  • Physiology

Cite this

Deletion of Slc26a6 alters the stoichiometry of apical Cl-/HCO3 - exchange in mouse pancreatic duct. / Ishiguro, Hiroshi; Song, Ying; Yamamoto, Akiko; Steward, Martin C.; Ko, Shigeru; Stewart, Andrew K.; Soleimani, Manoocher; Liu, Bai Chun; Kondo, Takaharu; Jin, Chun Xiang.

In: American Journal of Physiology - Cell Physiology, Vol. 303, No. 8, 15.10.2012.

Research output: Contribution to journalArticle

Ishiguro, H, Song, Y, Yamamoto, A, Steward, MC, Ko, S, Stewart, AK, Soleimani, M, Liu, BC, Kondo, T & Jin, CX 2012, 'Deletion of Slc26a6 alters the stoichiometry of apical Cl-/HCO3 - exchange in mouse pancreatic duct', American Journal of Physiology - Cell Physiology, vol. 303, no. 8. https://doi.org/10.1152/ajpcell.00151.2012
Ishiguro, Hiroshi ; Song, Ying ; Yamamoto, Akiko ; Steward, Martin C. ; Ko, Shigeru ; Stewart, Andrew K. ; Soleimani, Manoocher ; Liu, Bai Chun ; Kondo, Takaharu ; Jin, Chun Xiang. / Deletion of Slc26a6 alters the stoichiometry of apical Cl-/HCO3 - exchange in mouse pancreatic duct. In: American Journal of Physiology - Cell Physiology. 2012 ; Vol. 303, No. 8.
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AU - Yamamoto, Akiko

AU - Steward, Martin C.

AU - Ko, Shigeru

AU - Stewart, Andrew K.

AU - Soleimani, Manoocher

AU - Liu, Bai Chun

AU - Kondo, Takaharu

AU - Jin, Chun Xiang

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AB - To define the stoichiometry and molecular identity of the Cl-/HCO3 - exchanger in the apical membrane of pancreatic duct cells, changes in luminal pH and volume were measured simultaneously in interlobular pancreatic ducts isolated from wild-type and Slc26a6-null mice. Transepithelial fluxes of HCO3 - and Cl- were measured in the presence of anion gradients favoring rapid exchange of intracellular HCO3 - with luminal Cl- in cAMP-stimulated ducts. The flux ratio of Cl- absorption/ HCO3 - secretion was ~0.7 in wild-type ducts and ~1.4 in Slc26a6-/- ducts where a different Cl-/HCO3 - exchanger, most likely SLC26A3, was found to be active. Interactions between Cl-/HCO3 - exchange and cystic fibrosis transmembrane conductance regulator (CFTR) in cAMP-stimu-lated ducts were examined by measuring the recovery of intracellular pH after alkali-loading by acetate prepulse. Hyperpolarization induced by luminal application of CFTRinh-172 enhanced HCO3 - efflux across the apical membrane via SLC26A6 in wild-type ducts but significantly reduced HCO3 - efflux in Slc26a6-/- ducts. In microper-fused wild-type ducts, removal of luminal Cl-, or luminal application of dihydro-4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid to inhibit SLC26A6, caused membrane hyperpolarization, which was abolished in Slc26a6-/- ducts. In conclusion, we have demonstrated that deletion of Slc26a6 alters the apparent stoichiometry of apical Cl-/ HCO3 exchange in native pancreatic duct. Our results are consistent with SLC26A6 mediating 1:2 Cl-/HCO3 - exchange, and the exchanger upregulated in its absence, most probably SLC26A3, mediating 2:1 exchange.

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