Open AccessModulation of brain Na+ channels by a G-protein-coupled pathway.
Author(s) -
Y. Y. Ooi Jenny,
Ming Li,
William A. Catterall,
Todd Scheuer
Publication year - 1994
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.91.25.12351
Subject(s) - g protein , pertussis toxin , guanosine , gtp binding protein regulators , chinese hamster ovary cell , gtp' , g alpha subunit , cholera toxin , biophysics , biology , chemistry , protein subunit , microbiology and biotechnology , biochemistry , signal transduction , endocrinology , receptor , enzyme , gene
Na+ channels in acutely dissociated rat hippocampal neurons and in Chinese hamster ovary (CHO) cells transfected with a cDNA encoding the alpha subunit of rat brain type IIA Na+ channel (CNaIIA-1 cells) are modulated by guanine nucleotide binding protein (G protein)-coupled pathways under conditions of whole-cell voltage clamp. Activation of G proteins by 0.2-0.5 mM guanosine 5'-[gamma-thio]triphosphate (GTP[gamma S]), a nonhydrolyzable GTP analog, increased Na+ currents recorded in both cell types. The increase in current amplitude was caused by an 8- to 10-mV negative shift in the voltage dependence of both activation and inactivation. The effects of G-protein activators were blocked by treatment with pertussis toxin or guanosine 5'-[beta-thio]diphosphate (GDP[beta S]), a nonhydrolyzable GDP analog, but not by cholera toxin. GDP[beta S] (2 mM) alone had effects opposite those of GTP[gamma S], shifting Na(+)-channel gating 8-10 mV toward more-positive membrane potentials and suggesting that basal activation of G proteins in the absence of stimulation is sufficient to modulate Na+ channels. In CNaIIA-1 cells, thrombin, which activates pertussis toxin-sensitive G proteins in CHO cells, caused a further negative shift in the voltage dependence of Na(+)-channel activation and inactivation beyond that observed with GTP alone. The results in CNaIIA-1 cells indicate that the alpha subunit of the Na+ channel alone is sufficient to mediate G protein effects on gating. The modulation of Na+ channels via a G-protein-coupled pathway acting on Na(+)-channel alpha subunits may regulate electrical excitability through integration of different G-protein-coupled synaptic inputs.