Molecular mechanism of protein kinase C modulation of sodium channel alpha-subunits expressed in Xenopus oocytes.
The mechanism of modulation of sodium channel alpha-subunits (Type IIA) by a protein kinase C (PKC) activator was studied on single channel level. It was found that: (i) time constants for channel activation were prolonged; (ii) inactivation remained virtually unchanged; (iii) peak sodium inward current was reduced as evidenced by calculation of average sodium currents; and (iv) time constants for current activation and decay were prolonged. (i), (iii) and (iv) were voltage dependent, being most prominent at threshold potentials. The data show that a voltage dependent action on the activation gate can account for the observed reduction of peak inward sodium current and prolongation of current decay in macroscopic experiments.
Schreibmayer
W
W
Institute of Medical Physics and Biophysics, Karl-Franzens University Graz, Austria.
Dascal
N
N
Lotan
I
I
Wallner
M
M
Weigl
L
L
D000818:Animals; D008564:Membrane Potentials; D009865:Oocytes / Q000378:metabolism*; D011493:Protein Kinase C / Q000096:biosynthesis / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects / Q000201:enzymology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014982:Xenopus laevis / Q000378:metabolism*
D015222:Sodium Channels; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate