Modulation of Ca(2+)-channel currents by protein kinase C in adult rat sympathetic neurons

J Neurophysiol. 1994 Oct;72(4):1549-60. doi: 10.1152/jn.1994.72.4.1549.


1. Modulation of Ca(2+)-channel currents by phorbol-12-myristate-13-acetate (PMA) was investigated in acutely dissociated adult rat superior cervical ganglion neurons using the whole cell variant of the patch-clamp technique. 2. PMA (500 nM) increased the current amplitudes, accelerated the inactivation of step currents, retarded the deactivation of tail currents, and shifted the tail current activation to more negative potentials. 3. The effects of PMA were concentration and voltage dependent and mediated through activation of protein kinase C (PKC). PMA also increased Ca2+ currents recorded with the perforated patch technique. 4. PMA affected the N-type Ca2+ channels and an omega-conotoxin GVIA-resistant current component. Ca2+ currents affected by PMA were not sensitive to omega-agatoxin IVA or nimodipine. 5. PMA not only attenuated Ca(2+)-channel inhibition induced by alpha 2-adrenoceptor agonist, which modulates Ca2+ channels via a pertussis toxin (PTX)-sensitive pathway, but also attenuated current inhibition by vasoactive intestinal polypeptide, which modulates Ca2+ channels via a PTX-insensitive but cholera toxin-sensitive pathway. 6. PMA reversed Ca(2+)-channel inhibition induced by tonic activation of G-protein in the absence of neurotransmitter (even in neurons pretreated with PTX) or induced by activation of G-proteins with guanosine 5'-O-(3-thiotriphosphate) (GTP)-gamma-S. 7. Inhibition of phosphatase by okadaic acid or substitution of Ba2+ for Ca2+ in the external solutions accelerated the PMA effect. 8. Our results suggest that activation of PKC antagonizes G-protein mediated inhibition of Ca2+ channels by shifting Ca2+ channels from the "reluctant" state to the "willing" state. The G-proteins and, more likely, the N-type Ca2+ channels may be the target of PKC phosphorylation. Protein phosphatases may be involved in counteracting the PKC phosphorylation in rat sympathetic neurons.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Dose-Response Relationship, Drug
  • Enzyme Activation / drug effects
  • Enzyme Activation / physiology
  • Ethers, Cyclic / pharmacology
  • GTP-Binding Proteins / physiology
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology
  • Neurons / drug effects
  • Neurons / physiology
  • Okadaic Acid
  • Patch-Clamp Techniques
  • Pertussis Toxin
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / physiology*
  • Rats
  • Superior Cervical Ganglion / drug effects
  • Superior Cervical Ganglion / physiology*
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*
  • Tetradecanoylphorbol Acetate / pharmacology
  • Virulence Factors, Bordetella / pharmacology


  • Calcium Channels
  • Ethers, Cyclic
  • Virulence Factors, Bordetella
  • Okadaic Acid
  • Pertussis Toxin
  • Protein Kinase C
  • GTP-Binding Proteins
  • Tetradecanoylphorbol Acetate
  • Calcium