Abstract
Of 12 cell lines derived from human lung cancers, only Calu-3 cells showed high transepithelial resistance (Rte) and increases in short-circuit current (Isc) in response to mediators. Calu-3 cells formed polarized monolayers with tight junctions and Rte of approximately 100 omega.cm2. Baseline Isc was approximately 35 microA/cm2 and was increased by approximately 75 microA/cm2 on elevation of intracellular adenosine 3',5'-cyclic monophosphate (cAMP) by isoproterenol. Flux studies showed that the increase in Isc was due to Cl- secretion. Forskolin and permeant analogues of cAMP also increased Isc. Consistent with the presence of cAMP-dependent Cl- secretion, immunoprecipitation demonstrated the presence of the cystic fibrosis transmembrane conductance regulator (CFTR). Bradykinin, methacholine, trypsin, and histamine all transiently (15-30 s) elevated Isc, probably by increasing intracellular Ca concentration. Experiments in which the basolateral membrane was permeabilized with nystatin indicated that CFTR was substantially activated under baseline conditions and that Ca-activated Cl- channels were absent from the apical membrane. We anticipate that Calu-3 cells will prove useful in the study of Cl- secretion and other functions of human airway epithelial cells.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Bradykinin / pharmacology
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Bumetanide / pharmacology
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Calcimycin / pharmacology
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Cell Line
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Cell Membrane / drug effects
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Cell Membrane / physiology
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Cell Membrane / ultrastructure
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Cell Membrane Permeability
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Chloride Channels / analysis
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Chloride Channels / metabolism*
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Chlorides / metabolism*
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Colforsin / pharmacology*
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Cyclic AMP / metabolism*
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Cystic Fibrosis Transmembrane Conductance Regulator
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Cytoplasmic Granules / ultrastructure
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Desmosomes / ultrastructure
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Epithelium / drug effects
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Epithelium / physiology
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Epithelium / ultrastructure
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Histamine / pharmacology
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Humans
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Intercellular Junctions / physiology
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Intercellular Junctions / ultrastructure
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Isoproterenol / pharmacology*
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Kinetics
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Lung Neoplasms
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Membrane Proteins / analysis
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Membrane Proteins / drug effects
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Membrane Proteins / metabolism*
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Methacholine Chloride / pharmacology
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Microscopy, Electron
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Nystatin / pharmacology
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Ouabain / pharmacology
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Sodium / metabolism
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Trypsin / pharmacology
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Tumor Cells, Cultured
Substances
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CFTR protein, human
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Chloride Channels
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Chlorides
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Membrane Proteins
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Methacholine Chloride
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Bumetanide
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Cystic Fibrosis Transmembrane Conductance Regulator
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Nystatin
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Colforsin
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Calcimycin
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Ouabain
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Histamine
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Sodium
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Cyclic AMP
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Trypsin
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Isoproterenol
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Bradykinin