TY - JOUR
T1 - Deletion of Slc26a6 alters the stoichiometry of apical Cl-/HCO3- exchange in mouse pancreatic duct
AU - Ishiguro, Hiroshi
AU - Song, Ying
AU - Yamamoto, Akiko
AU - Steward, Martin C.
AU - Ko, Shigeru B H
AU - Stewart, Andrew K.
AU - Soleimani, Manoocher
AU - Liu, Bai Chun
AU - Kondo, Takaharu
AU - Jin, Chun Xiang
PY - 2012/10/15
Y1 - 2012/10/15
N2 - 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. © 2012 the American Physiological Society.
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. © 2012 the American Physiological Society.
KW - Isolated pancreatic duct
KW - Microperfusion
KW - Micropuncture
KW - Stoichiometry
U2 - 10.1152/ajpcell.00151.2012
DO - 10.1152/ajpcell.00151.2012
M3 - Article
SN - 0363-6143
VL - 303
SP - C815-C824
JO - American Journal of Physiology: Cell Physiology
JF - American Journal of Physiology: Cell Physiology
IS - 8
ER -
