Protein kinase C is not necessary for peptide-induced suppression of M current or for desensitization of the peptide receptors.
Frog sympathetic ganglion cells were studied under whole-cell voltage clamp to determine whether protein kinase C (PKC) mediates peptide-induced suppression of M current (IM) or desensitization of peptide receptors. Low concentrations (10 mM) of chicken II luteinizing hormone-releasing hormone (LHRH) or substance P (SP) suppressed IM; in addition, higher concentrations (1 microM) desensitized receptors. Desensitization is homologous (specific to the peptide) and lasts at least 25 min. Two stimulators of PKC, phorbol 12-myristate 13-acetate and dioctanoylglycerol, partially depressed IM and occluded the response to SP but not to LHRH. The two actions of PKC stimulators were blocked by PKC inhibitors (staurosporine, a pseudosubstrate peptide, and H-7), but SP- and LHRH-mediated suppression of IM and receptor desensitization were not affected. Thus, we conclude that PKC is not necessary for normal IM suppression or receptor desensitization.
Bosma
M M
MM
Department of Physiology and Biophysics, University of Washington Medical School, Seattle 98195.
Hille
B
B
D000818:Animals; D004553:Electric Conductivity; D005728:Ganglia, Sympathetic / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D011894:Rana pipiens; D011984:Sensory Receptor Cells / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D013373:Substance P; D007987:Gonadotropin-Releasing Hormone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium