title: Ion-transport properties of cultured bovine pancreatic duct epithelial cells.
abstract: Primary cultures of bovine pancreatic duct epithelial cells grown on permeable supports exhibit electrogenic transepithelial ion transport. The short-circuit current (I(sc)) generated by unstimulated duct cell monolayers and the increase in I(sc) elicited by increased levels of cyclic adenosine monophosphate (cAMP) were greater in monolayers bathed by bicarbonate-containing solution compared with monolayers bathed by nominally bicarbonate-free solution. An inhibitor of epithelial sodium channels (amiloride, 10 microM) had no effect on I(sc), whereas a Cl- channel blocker, N-phenylanthranilic acid (DPC; 1 mM), reduced the forskolin-stimulated I(sc) by approximately 50% in the absence or presence of bicarbonate. Bumetanide (an inhibitor of Na+,K+,2Cl- cotransport activity; 10 microM) reduced forskolin-stimulated I(sc) by 49 +/- 6% in bicarbonate-free bathing solution and by only 18 +/- 1% in bicarbonate-containing solution. Measurements of unidirectional 36Cl- flux across short-circuited ductal monolayers in a bicarbonate-containing solution revealed that net Cl- secretion accounted for the I(sc) during secretin stimulation. However, the basal I(sc) and the I(sc) measured during exposure to secretin plus bumetanide were significantly greater than net Cl- flux. The permeability coefficient for [14C]acetate (a surrogate tracer for bicarbonate) measured in the secretory direction was approximately 1.5-fold greater than the permeability coefficient measured in the absorptive direction, indicating net secretion. These results suggest that primary cultures of bovine pancreatic duct epithelial cells secrete both Cl- and HCO3-.
authors.affiliation: Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio, USA.
authors.forename: C U
authors.initials: CU
authors.lastname: Cotton
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002034:Bumetanide / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D017136:Ion Transport; D008564:Membrane Potentials; D010183:Pancreatic Ducts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D062367:ortho-Aminobenzoates / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D002121:Calcium Channel Blockers; D018118:Chloride Channels; D002712:Chlorides; D062367:ortho-Aminobenzoates; D002034:Bumetanide; D005576:Colforsin; C001209:fenamic acid; D000242:Cyclic AMP