Dual effects of diazoxide on ATP-K+ currents recorded from an insulin-secreting cell line

R. Z. Kozlowski, C. N. Hales, M. L. J. Ashford

    Research output: Contribution to journalArticle

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    Abstract

    1. The effects of diazoxide on ATP-K+ channel currents, recorded from the insulin-secreting cell line, CRI-G1, were studied using patch-clamp techniques.
    2. Under current-clamp recording conditions diazoxide (0.6 mM), inhibited action potential activity and hyperpolarized CRI-G1 cells with a concomitant increase in membrane conductance. Recordings from voltage-clamped whole-cells and isolated patches indicate that activation of ATP-K+ channel currents underlie these effects.
    3. Diazoxide elicited an activation of ATP-K+ channels which had been partially inhibited by ATP, on application to either surface of the plasma membrane, although it was more effective when applied directly to the cytoplasmic side. Activation of the ATP-K+ currents involves an increase in the single channel open-state probability and an apparent increase in the number of functional channels.
    4. Activation was observed only when Mg-ATP was present in the cytoplasmic bathing solution. There was no activation of currents by diazoxide when ATP, in the absence of Mg2+ ions, or Mg-AMP-PNP was present to inhibit the ATP-K+ channels.
    5. In the absence of ATP and Mg2+ ions in the cytoplasmic bathing solution, diazoxide (0.6 mM) produced an inhibition of ATP-K+ currents.
    6. Cromakalim (BRL 34915) at 10 µM and 100 µM had no significant effects on ATP-K+ currents.
    7. It is concluded that diazoxide-induced activation of ATP-K+ channel currents probably involves phosphorylation of the channel or some closely associated membrane protein.

    Original languageEnglish
    Pages (from-to)1039-1050
    Number of pages12
    JournalBritish Journal of Pharmacology
    Volume97
    Issue number4
    DOIs
    Publication statusPublished - Aug 1989

    Fingerprint

    Diazoxide
    Insulin-Secreting Cells
    Adenosine Triphosphate
    Cell Line
    Cromakalim
    Adenylyl Imidodiphosphate
    Ions
    Action Potentials
    Membrane Proteins

    Keywords

    • Animals
    • Benzopyrans
    • Diazoxide
    • Cromakalim
    • Islets of Langerhans
    • Pyrroles
    • Insulin
    • Potassium Channels
    • Rats
    • Biotransformation
    • Cells, Cultured
    • Membrane Potentials
    • Adenosine Triphosphate
    • Solutions
    • Magnesium
    • Cell Line

    Cite this

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    title = "Dual effects of diazoxide on ATP-K+ currents recorded from an insulin-secreting cell line",
    abstract = "1. The effects of diazoxide on ATP-K+ channel currents, recorded from the insulin-secreting cell line, CRI-G1, were studied using patch-clamp techniques. 2. Under current-clamp recording conditions diazoxide (0.6 mM), inhibited action potential activity and hyperpolarized CRI-G1 cells with a concomitant increase in membrane conductance. Recordings from voltage-clamped whole-cells and isolated patches indicate that activation of ATP-K+ channel currents underlie these effects. 3. Diazoxide elicited an activation of ATP-K+ channels which had been partially inhibited by ATP, on application to either surface of the plasma membrane, although it was more effective when applied directly to the cytoplasmic side. Activation of the ATP-K+ currents involves an increase in the single channel open-state probability and an apparent increase in the number of functional channels. 4. Activation was observed only when Mg-ATP was present in the cytoplasmic bathing solution. There was no activation of currents by diazoxide when ATP, in the absence of Mg2+ ions, or Mg-AMP-PNP was present to inhibit the ATP-K+ channels. 5. In the absence of ATP and Mg2+ ions in the cytoplasmic bathing solution, diazoxide (0.6 mM) produced an inhibition of ATP-K+ currents. 6. Cromakalim (BRL 34915) at 10 µM and 100 µM had no significant effects on ATP-K+ currents. 7. It is concluded that diazoxide-induced activation of ATP-K+ channel currents probably involves phosphorylation of the channel or some closely associated membrane protein.",
    keywords = "Animals, Benzopyrans, Diazoxide, Cromakalim, Islets of Langerhans, Pyrroles, Insulin, Potassium Channels, Rats, Biotransformation, Cells, Cultured, Membrane Potentials, Adenosine Triphosphate, Solutions, Magnesium, Cell Line",
    author = "Kozlowski, {R. Z.} and Hales, {C. N.} and Ashford, {M. L. J.}",
    year = "1989",
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    language = "English",
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    issn = "0007-1188",
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    Dual effects of diazoxide on ATP-K+ currents recorded from an insulin-secreting cell line. / Kozlowski, R. Z.; Hales, C. N.; Ashford, M. L. J.

    In: British Journal of Pharmacology, Vol. 97, No. 4, 08.1989, p. 1039-1050.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Dual effects of diazoxide on ATP-K+ currents recorded from an insulin-secreting cell line

    AU - Kozlowski, R. Z.

    AU - Hales, C. N.

    AU - Ashford, M. L. J.

    PY - 1989/8

    Y1 - 1989/8

    N2 - 1. The effects of diazoxide on ATP-K+ channel currents, recorded from the insulin-secreting cell line, CRI-G1, were studied using patch-clamp techniques. 2. Under current-clamp recording conditions diazoxide (0.6 mM), inhibited action potential activity and hyperpolarized CRI-G1 cells with a concomitant increase in membrane conductance. Recordings from voltage-clamped whole-cells and isolated patches indicate that activation of ATP-K+ channel currents underlie these effects. 3. Diazoxide elicited an activation of ATP-K+ channels which had been partially inhibited by ATP, on application to either surface of the plasma membrane, although it was more effective when applied directly to the cytoplasmic side. Activation of the ATP-K+ currents involves an increase in the single channel open-state probability and an apparent increase in the number of functional channels. 4. Activation was observed only when Mg-ATP was present in the cytoplasmic bathing solution. There was no activation of currents by diazoxide when ATP, in the absence of Mg2+ ions, or Mg-AMP-PNP was present to inhibit the ATP-K+ channels. 5. In the absence of ATP and Mg2+ ions in the cytoplasmic bathing solution, diazoxide (0.6 mM) produced an inhibition of ATP-K+ currents. 6. Cromakalim (BRL 34915) at 10 µM and 100 µM had no significant effects on ATP-K+ currents. 7. It is concluded that diazoxide-induced activation of ATP-K+ channel currents probably involves phosphorylation of the channel or some closely associated membrane protein.

    AB - 1. The effects of diazoxide on ATP-K+ channel currents, recorded from the insulin-secreting cell line, CRI-G1, were studied using patch-clamp techniques. 2. Under current-clamp recording conditions diazoxide (0.6 mM), inhibited action potential activity and hyperpolarized CRI-G1 cells with a concomitant increase in membrane conductance. Recordings from voltage-clamped whole-cells and isolated patches indicate that activation of ATP-K+ channel currents underlie these effects. 3. Diazoxide elicited an activation of ATP-K+ channels which had been partially inhibited by ATP, on application to either surface of the plasma membrane, although it was more effective when applied directly to the cytoplasmic side. Activation of the ATP-K+ currents involves an increase in the single channel open-state probability and an apparent increase in the number of functional channels. 4. Activation was observed only when Mg-ATP was present in the cytoplasmic bathing solution. There was no activation of currents by diazoxide when ATP, in the absence of Mg2+ ions, or Mg-AMP-PNP was present to inhibit the ATP-K+ channels. 5. In the absence of ATP and Mg2+ ions in the cytoplasmic bathing solution, diazoxide (0.6 mM) produced an inhibition of ATP-K+ currents. 6. Cromakalim (BRL 34915) at 10 µM and 100 µM had no significant effects on ATP-K+ currents. 7. It is concluded that diazoxide-induced activation of ATP-K+ channel currents probably involves phosphorylation of the channel or some closely associated membrane protein.

    KW - Animals

    KW - Benzopyrans

    KW - Diazoxide

    KW - Cromakalim

    KW - Islets of Langerhans

    KW - Pyrroles

    KW - Insulin

    KW - Potassium Channels

    KW - Rats

    KW - Biotransformation

    KW - Cells, Cultured

    KW - Membrane Potentials

    KW - Adenosine Triphosphate

    KW - Solutions

    KW - Magnesium

    KW - Cell Line

    U2 - 10.1111/j.1476-5381.1989.tb12560.x

    DO - 10.1111/j.1476-5381.1989.tb12560.x

    M3 - Article

    C2 - 2676059

    VL - 97

    SP - 1039

    EP - 1050

    JO - British Journal of Pharmacology

    JF - British Journal of Pharmacology

    SN - 0007-1188

    IS - 4

    ER -