Abstract
The regulation of chloride conductance was investigated in the T84 human colon carcinoma cell line by the quenching of the fluorescent probe 6-methoxy-N-(3-sulfopropyl)quinolinium. The permeable cAMP analog 8-Br-cAMP (100 microM) and the calcium ionophore ionomycin (1 microM) activate a chloride conductance. A prolonged (4 h) preincubation of cells with phorbol 12-myristate 13-acetate (100 nM) or with the diacylglycerol analog 1-oleoyl-2-acetyl-glycerol (100 microM): (i) down-modulates to almost zero the protein kinase C activity in the membranes; (ii) inhibits the activation of the chloride conductance mediated by 8-Br-cAMP but not by calcium; (iii) reduces the mRNA without changing the expression of the protein product of the cystic fibrosis gene. The data suggest that PKC is essential for the activation of the cAMP-dependent chloride conductance in T84 cells.
MeSH terms
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8-Bromo Cyclic Adenosine Monophosphate / pharmacology
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Biological Transport
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Chloride Channels
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Chlorides / metabolism*
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Colonic Neoplasms
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Cyclic AMP / pharmacology*
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Cystic Fibrosis / metabolism*
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Cystic Fibrosis Transmembrane Conductance Regulator
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Diglycerides / pharmacology
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Down-Regulation
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Electric Conductivity
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Fluorescence
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Fluorescent Dyes
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Humans
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Ionomycin / pharmacology
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Membrane Proteins / drug effects
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Membrane Proteins / metabolism*
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Protein Kinase C / metabolism*
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Protein Kinases / metabolism
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Quinolinium Compounds
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RNA, Messenger / biosynthesis
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Tetradecanoylphorbol Acetate / 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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Diglycerides
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Fluorescent Dyes
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Membrane Proteins
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Quinolinium Compounds
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RNA, Messenger
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Cystic Fibrosis Transmembrane Conductance Regulator
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8-Bromo Cyclic Adenosine Monophosphate
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Ionomycin
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6-methoxy-N-(3-sulfopropyl)quinolinium
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1-oleoyl-2-acetylglycerol
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Cyclic AMP
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Protein Kinases
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Protein Kinase C
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Tetradecanoylphorbol Acetate