Positive regulation by protein kinase C of slow Na current in Xenopus oocytes.
The slow inward Na current observed during sustained depolarization of the Xenopus oocyte membrane is due to a complex mechanism described as the induction of the channels. The present work investigates the role of protein phosphorylation in Na channel function. Injection of alkaline phosphatase in the oocytes decreased inward current. Therefore, the possible involvement of protein kinase in Na channel induction was explored. Treatment of oocytes with two activators of protein kinase C (PKC) resulted in enhanced Na current amplitude, whereas the treatment of oocytes with two potent PKC inhibitors decreased the inward current. These results imply that PKC phosphorylation is a fundamental step of Na channel induction. The possibility that the depolarization of the oocyte membrane may be the factor involved in PKC activation is discussed.
Charpentier
G
G
Laboratoire de Neurobiologie Cellulaire, Uniersité de Picardie Jules Verne, Faculté des Sciences, Amiens, France.
Fournier
F
F
Behue
N
N
Marlot
D
D
Brule
G
G
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D019311:Staurosporine; D013629:Tamoxifen / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014982:Xenopus laevis
D000470:Alkaloids; D004075:Diglycerides; D010703:Phorbol Esters; D015222:Sodium Channels; D013629:Tamoxifen; C008876:phorbol-12,13-didecanoate; D013779:Tetrodotoxin; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate