Abstract
Using an 125I- efflux assay, we have studied the expression of various types of chloride channels in isolated neonatal rat cardiomyocytes. Three different classes of anion conductances were distinguished: (1) a Ca(2+)-sensitive Cl- conductance, triggered upon stimulation of the cells with endothelin-1 or Ca(2+)-ionophore; (2) a cAMP/protein kinase A-operated Cl- conductance, activated by addition of forskolin. This anion channel could be identified as the Cystic Fibrosis Transmembrane conductance Regulator (CFTR-CI- channel) by Western blotting as well as by its enhanced activity in cultures pretreated with the tyrosine kinase inhibitor genistein; (3) a distinct class of cell volume-regulated Cl- channels, potentiated in the presence of endothelin-1 or the phosphotyrosine phosphatase inhibitor pervanadate. The potential role of each class of Cl- channels in the generation and/or modulation of action potentials as well as in maintaining cell volume is discussed.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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1-Methyl-3-isobutylxanthine / pharmacology
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Animals
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Animals, Newborn
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Calcimycin / pharmacology
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Calcium / metabolism
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Cells, Cultured
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Chloride Channels / biosynthesis*
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Chloride Channels / physiology
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Colforsin / pharmacology
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Cystic Fibrosis Transmembrane Conductance Regulator / biosynthesis
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Cystic Fibrosis Transmembrane Conductance Regulator / physiology
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Endothelins / pharmacology
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Enzyme Inhibitors / pharmacology
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Gene Expression* / drug effects
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Genistein
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Heart / drug effects*
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Heart / physiology
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Hypertonic Solutions
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Hypotonic Solutions
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Iodides / metabolism*
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Iodine Radioisotopes
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Isoflavones / pharmacology
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Myocardium / metabolism*
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Protein Tyrosine Phosphatases / antagonists & inhibitors
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Protein-Tyrosine Kinases / antagonists & inhibitors
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Rats
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Rats, Wistar
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Signal Transduction
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Vanadates / pharmacology
Substances
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Chloride Channels
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Endothelins
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Enzyme Inhibitors
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Hypertonic Solutions
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Hypotonic Solutions
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Iodides
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Iodine Radioisotopes
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Isoflavones
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pervanadate
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Cystic Fibrosis Transmembrane Conductance Regulator
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Colforsin
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Calcimycin
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Vanadates
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Genistein
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Protein-Tyrosine Kinases
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Protein Tyrosine Phosphatases
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Calcium
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1-Methyl-3-isobutylxanthine