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Forskolin prolongs action potential duration and blocks potassium current in embryonic chick sensory neurons

K Dunlap

    Pflugers Archiv : European Journal of Physiology
    |February 1, 1985
    PubMed

    Insights

    Forskolin, a cyclic adenosine monophosphate (cAMP) activator, increases action potential duration in chick sensory neurons by activating adenylate cyclase. This effect is distinct from norepinephrine

    Area of Science:

    • Neuroscience
    • Cellular Biology
    • Pharmacology

    Background:

    • Voltage-dependent ion channels are crucial for neuronal function.
    • Internal cyclic adenosine monophosphate (cAMP) levels can modulate these channels.
    • Embryonic chick sensory neurons provide a model for studying neuronal excitability.

    Purpose of the Study:

    • To investigate the role of internal cyclic adenosine monophosphate (cAMP) in modulating voltage-dependent channels.
    • To determine if forskolin, an adenylate cyclase activator, affects neuronal action potential duration.
    • To compare the effects of forskolin with other modulators like capsaicin and norepinephrine.

    Main Methods:

    • Application of forskolin and cholera toxin to embryonic chick sensory neurons in vitro.
    • Measurement of action potential duration and voltage-dependent outward currents.
    • Use of 2',5'-dideoxyadenosine to inhibit adenylate cyclase activity.
    • Voltage-clamp techniques to analyze membrane currents.

    Main Results:

    • Forskolin caused dose-dependent, reversible increases in action potential duration.
    • The forskolin-induced effect was blocked by 2',5'-dideoxyadenosine, indicating adenylate cyclase involvement.
    • Cholera toxin also increased action potential duration.
    • Forskolin decreased voltage-dependent outward current in voltage-clamped neurons.
    • Forskolin's effects mimicked capsaicin but contrasted with norepinephrine's previously reported actions.

    Conclusions:

    • Internal cAMP modulation, via adenylate cyclase activation, significantly impacts action potential duration in these neurons.
    • Forskolin's actions on voltage-dependent channels are distinct from those of norepinephrine.
    • Adenylate cyclase activation is likely not involved in norepinephrine's modulation of calcium channels.

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