title: Characterization of vectorial chloride transport pathways in the human pancreatic duct adenocarcinoma cell line HPAF.
abstract: Pancreatic duct cells express a Ca2+-activated Cl- conductance (CaCC), upregulation of which may be beneficial to patients with cystic fibrosis. Here, we report that HPAF, a human pancreatic ductal adenocarcinoma cell line that expresses CaCC, develops into a high-resistance, anion-secreting epithelium. Mucosal ATP (50 microM) caused a fourfold increase in short-circuit current (Isc), a hyperpolarization of transepithelial potential difference (from -4.9 +/- 0.73 to -8.5 +/- 0.84 mV), and a fall in resistance to less than one-half of resting values. The effects of ATP were inhibited by mucosal niflumic acid (100 microM), implicating an apical CaCC in the response. RT-PCR indicated expression of hClC-2, hClC-3, and hClC-5, but surprisingly not hCLCA-1 or hCLCA-2. K+ channel activity was necessary to maintain the ATP-stimulated Isc. Using a pharmacological approach, we found evidence for two types of K+ channels in the mucosal and serosal membranes of HPAF cells, one activated by chlorzoxazone (500 microM) and sensitive to clotrimazole (30 microM), as well as one blocked by clofilium (100 microM) but not chromanol 293B (5 microM). RT-PCR indicated expression of the Ca2+-activated K+ channel KCNN4, as well as the acid-sensitive, four transmembrane domain, two pore K+ channel, KCNK5 (hTASK-2). Western blot analysis verified the expression of CLC channels, as well as KCNK5. We conclude that HPAF will be a useful model system for studying channels pertinent to anion secretion in human pancreatic duct cells.
authors.affiliation: Department of Physiology, The Johns Hopkins University School of Medicine, Rm. 202C Physiology, 725 North Wolfe St., Baltimore, MD 21205, USA. pfong@jhmi.edu
authors.forename: Peying
authors.initials: P
authors.lastname: Fong
authors.forename: Barry E
authors.initials: BE
authors.lastname: Argent
authors.forename: William B
authors.initials: WB
authors.lastname: Guggino
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gray
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D020013:Calcium Signaling / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism*; D018118:Chloride Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D017097:Electric Impedance; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D008954:Models, Biological; D009544:Niflumic Acid / Q000494:pharmacology; D010183:Pancreatic Ducts / Q000378:metabolism* / Q000503:physiopathology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D009544:Niflumic Acid; D000255:Adenosine Triphosphate