Chloride channels and anion fluxes in a human colonic epithelium (HCA-7)

R. M. Henderson, M. L. J. Ashford, L. J. MacVinish, A. W. Cuthbert

    Research output: Contribution to journalArticle

    14 Citations (Scopus)

    Abstract

    1. Colonic epithelial cells, derived from a human adenocarcinoma (HCA-7), were examined by the patch clamp technique. 2. Outwardly rectifying anion (Cl-) channels were identified in the apical membrane. The conductance was g(in) approximately 26 pS, g(out) approximately 40 pS. The open state probability of the channels increased with depolarization and the selectivity for Cl- over K+ (PCl/PK) was approximately 7.5. 3. The channels were sensitive to intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP, 0.1 mM), but not to Ca2+ (at concentrations up to 1 mM). At depolarized potentials the channels were blocked by pirentanide (1-5 microM) applied intracellularly. 4. HCA-7 monolayers loaded with 125I- (as a marker for Cl-) were used to measure I- efflux and converted to instantaneous rate constants. 5. The rate constant for I- efflux was increased by forskolin and lysylbradykinin (LBK). The effects of forskolin were not effected by BAPTA (an intracellular calcium chelator). The effects of LBK were inhibited by BAPTA and by Ba2+, indicating that LBK raised intracellular Ca2+ (Cai) which activates Ca(2+)-sensitive K-channels, the latter being blocked by Ba2+. 6. Although it cannot be conclusively proved that the outwardly rectifying chloride channels described here are solely or partially responsible for the increased anion efflux or transepithelial chloride secretion, the channels are likely to be more relevant for cyclic AMP-requiring rather than Ca(2+)-requiring secretagogues.
    Original languageEnglish
    Pages (from-to)109-114
    Number of pages6
    JournalBritish Journal of Pharmacology
    Volume106
    Issue number1
    Publication statusPublished - May 1992

    Fingerprint

    Chloride Channels
    Colforsin
    Cyclic AMP
    Anions
    Epithelium
    Patch-Clamp Techniques
    Adenosine
    Adenocarcinoma
    Epithelial Cells
    Membranes
    1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
    Calcium Chelating Agents

    Keywords

    • Calcium
    • Egtazic Acid
    • Electric Conductivity
    • Humans
    • Cyclic AMP
    • Chlorides
    • Ion Channels
    • Membrane Proteins
    • Potassium Channels
    • Kallidin
    • Tumor Cells, Cultured
    • Colon
    • Barium
    • Epithelium
    • Adenocarcinoma
    • Sulfonamides
    • Chloride Channels
    • Forskolin

    Cite this

    Henderson, R. M., Ashford, M. L. J., MacVinish, L. J., & Cuthbert, A. W. (1992). Chloride channels and anion fluxes in a human colonic epithelium (HCA-7). British Journal of Pharmacology, 106(1), 109-114.
    Henderson, R. M. ; Ashford, M. L. J. ; MacVinish, L. J. ; Cuthbert, A. W. / Chloride channels and anion fluxes in a human colonic epithelium (HCA-7). In: British Journal of Pharmacology. 1992 ; Vol. 106, No. 1. pp. 109-114.
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    abstract = "1. Colonic epithelial cells, derived from a human adenocarcinoma (HCA-7), were examined by the patch clamp technique. 2. Outwardly rectifying anion (Cl-) channels were identified in the apical membrane. The conductance was g(in) approximately 26 pS, g(out) approximately 40 pS. The open state probability of the channels increased with depolarization and the selectivity for Cl- over K+ (PCl/PK) was approximately 7.5. 3. The channels were sensitive to intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP, 0.1 mM), but not to Ca2+ (at concentrations up to 1 mM). At depolarized potentials the channels were blocked by pirentanide (1-5 microM) applied intracellularly. 4. HCA-7 monolayers loaded with 125I- (as a marker for Cl-) were used to measure I- efflux and converted to instantaneous rate constants. 5. The rate constant for I- efflux was increased by forskolin and lysylbradykinin (LBK). The effects of forskolin were not effected by BAPTA (an intracellular calcium chelator). The effects of LBK were inhibited by BAPTA and by Ba2+, indicating that LBK raised intracellular Ca2+ (Cai) which activates Ca(2+)-sensitive K-channels, the latter being blocked by Ba2+. 6. Although it cannot be conclusively proved that the outwardly rectifying chloride channels described here are solely or partially responsible for the increased anion efflux or transepithelial chloride secretion, the channels are likely to be more relevant for cyclic AMP-requiring rather than Ca(2+)-requiring secretagogues.",
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    author = "Henderson, {R. M.} and Ashford, {M. L. J.} and MacVinish, {L. J.} and Cuthbert, {A. W.}",
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    Henderson, RM, Ashford, MLJ, MacVinish, LJ & Cuthbert, AW 1992, 'Chloride channels and anion fluxes in a human colonic epithelium (HCA-7)', British Journal of Pharmacology, vol. 106, no. 1, pp. 109-114.

    Chloride channels and anion fluxes in a human colonic epithelium (HCA-7). / Henderson, R. M.; Ashford, M. L. J.; MacVinish, L. J.; Cuthbert, A. W.

    In: British Journal of Pharmacology, Vol. 106, No. 1, 05.1992, p. 109-114.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Chloride channels and anion fluxes in a human colonic epithelium (HCA-7)

    AU - Henderson, R. M.

    AU - Ashford, M. L. J.

    AU - MacVinish, L. J.

    AU - Cuthbert, A. W.

    PY - 1992/5

    Y1 - 1992/5

    N2 - 1. Colonic epithelial cells, derived from a human adenocarcinoma (HCA-7), were examined by the patch clamp technique. 2. Outwardly rectifying anion (Cl-) channels were identified in the apical membrane. The conductance was g(in) approximately 26 pS, g(out) approximately 40 pS. The open state probability of the channels increased with depolarization and the selectivity for Cl- over K+ (PCl/PK) was approximately 7.5. 3. The channels were sensitive to intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP, 0.1 mM), but not to Ca2+ (at concentrations up to 1 mM). At depolarized potentials the channels were blocked by pirentanide (1-5 microM) applied intracellularly. 4. HCA-7 monolayers loaded with 125I- (as a marker for Cl-) were used to measure I- efflux and converted to instantaneous rate constants. 5. The rate constant for I- efflux was increased by forskolin and lysylbradykinin (LBK). The effects of forskolin were not effected by BAPTA (an intracellular calcium chelator). The effects of LBK were inhibited by BAPTA and by Ba2+, indicating that LBK raised intracellular Ca2+ (Cai) which activates Ca(2+)-sensitive K-channels, the latter being blocked by Ba2+. 6. Although it cannot be conclusively proved that the outwardly rectifying chloride channels described here are solely or partially responsible for the increased anion efflux or transepithelial chloride secretion, the channels are likely to be more relevant for cyclic AMP-requiring rather than Ca(2+)-requiring secretagogues.

    AB - 1. Colonic epithelial cells, derived from a human adenocarcinoma (HCA-7), were examined by the patch clamp technique. 2. Outwardly rectifying anion (Cl-) channels were identified in the apical membrane. The conductance was g(in) approximately 26 pS, g(out) approximately 40 pS. The open state probability of the channels increased with depolarization and the selectivity for Cl- over K+ (PCl/PK) was approximately 7.5. 3. The channels were sensitive to intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP, 0.1 mM), but not to Ca2+ (at concentrations up to 1 mM). At depolarized potentials the channels were blocked by pirentanide (1-5 microM) applied intracellularly. 4. HCA-7 monolayers loaded with 125I- (as a marker for Cl-) were used to measure I- efflux and converted to instantaneous rate constants. 5. The rate constant for I- efflux was increased by forskolin and lysylbradykinin (LBK). The effects of forskolin were not effected by BAPTA (an intracellular calcium chelator). The effects of LBK were inhibited by BAPTA and by Ba2+, indicating that LBK raised intracellular Ca2+ (Cai) which activates Ca(2+)-sensitive K-channels, the latter being blocked by Ba2+. 6. Although it cannot be conclusively proved that the outwardly rectifying chloride channels described here are solely or partially responsible for the increased anion efflux or transepithelial chloride secretion, the channels are likely to be more relevant for cyclic AMP-requiring rather than Ca(2+)-requiring secretagogues.

    KW - Calcium

    KW - Egtazic Acid

    KW - Electric Conductivity

    KW - Humans

    KW - Cyclic AMP

    KW - Chlorides

    KW - Ion Channels

    KW - Membrane Proteins

    KW - Potassium Channels

    KW - Kallidin

    KW - Tumor Cells, Cultured

    KW - Colon

    KW - Barium

    KW - Epithelium

    KW - Adenocarcinoma

    KW - Sulfonamides

    KW - Chloride Channels

    KW - Forskolin

    M3 - Article

    VL - 106

    SP - 109

    EP - 114

    JO - British Journal of Pharmacology

    JF - British Journal of Pharmacology

    SN - 0007-1188

    IS - 1

    ER -