Cyclic AMP-dependent phosphorylation of voltage-sensitive sodium channels in primary cultures of rat brain cells
The ..cap alpha.. subunit of the voltage-sensitive Na channel from rat brain is phosphorylated by cAMP-dependent protein kinase in purified preparations and in synaptosomes. The authors have begun to study cAMP-dependent phosphorylation of Na channels in intact cells. Rat brain cells collected at embryonic day 15 and maintained in culture for approximately 21 days were subjected to treatments designed to increase intracellular cAMP. Cells were solubilized and Na channels were isolated by immunoprecipitation, then rephosphorylated with the catalytic subunit of cAMP-dependent protein kinase and /sup 32/P-ATP, to allow incorporation of /sup 32/P into available cAMP-dependent phosphorylation sites of Na channels. The amount of /sup 32/P incorporated into channel is inversely proportional to the extent of endogenous phosphorylation. Treatment of cells with forskolin inhibited rephosphorylation of Na channels, indicating that enhanced endogenous phosphorylation of channels had occurred. The effect of forskolin on cell surface Na channels occurred rapidly, was sustained over 30 min., and was half-maximal at 6..mu..M. 8-Br-cAMP, (EC/sub 50/-5mM) and isobutylmethylxanthine (EC/sub 50/-60..mu..M) also caused inhibition of /sup 32/P incorporation into Na channels. These results indicate that the extent of cAMP-dependent phosphorylation of voltage-sensitive Na channels in intact brain neurons is modified by changes in intracellular levels of cAMP.
- Research Organization:
- Univ. of Washington, Seattle
- OSTI ID:
- 6943038
- Report Number(s):
- CONF-8604222-; TRN: 87-007028
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques