cAMP-regulated whole cell chloride currents in pancreatic duct cells.
Using the whole cell configuration of the patch-clamp technique, we have identified an adenosine 3',5'-cyclic monophosphate (cAMP)-regulated chloride conductance in pancreatic duct cells. Basal whole cell currents in single isolated cells were very low (approximately 5 pA/pF) but could be stimulated 17-fold by elevation of intracellular cAMP. The cAMP-activated currents exhibited 1) a high chloride selectivity, 2) a near linear current-voltage relationship, 3) time and voltage independence, 4) block by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) but not by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), and 5) an anion selectivity sequence based on permeability ratios of SCN > NO3 > Br > Cl > I > HCO3 > F > ClO4 > gluconate. Currents in single cells ran down within a few minutes; however, stable chloride currents could be recorded from duct cell clusters in which four or five cells were in electrical communication. We present evidence suggesting that these cAMP-regulated currents are carried by cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels. Physiologically, these CFTR channels act in parallel with chloride-bicarbonate exchangers to facilitate bicarbonate secretion across the apical plasma membrane of the duct cell.
Gray
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MA
Department of Physiological Sciences, University Medical School, Newcastle upon Tyne, United Kingdom.
Plant
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Argent
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001965:Bromides / Q000493:pharmacokinetics; D002450:Cell Communication / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability / Q000502:physiology; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism* / Q000493:pharmacokinetics; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D007455:Iodine / Q000493:pharmacokinetics; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology; D009566:Nitrates / Q000493:pharmacokinetics; D009579:Nitrobenzoates / Q000494:pharmacology; D010183:Pancreatic Ducts / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D001965:Bromides; D002712:Chlorides; D007473:Ion Channels; D008565:Membrane Proteins; D009566:Nitrates; D009579:Nitrobenzoates; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D007455:Iodine; D000242:Cyclic AMP; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid