The role of G proteins in regulation of non-voltage-gated Na+channels in human myeloid leukemia K562 cells was studied by inside-out patch-clamp method. Na+channels were activated by non-hydrolyzable analog of guanosine triphosphate (GTP), GTPγS, known to activate both heterotrimeric and small G proteins. Channel activity was not affected by aluminum fluoride that indiscriminately activates heterotrimeric G proteins. The effect of GTPγS was prevented by phalloidin and by G-actin, both interfering with actin disassembly, which indicates that GTPγS-induced channel activation was likely due to microfilament disruption. GTPγS-activated channels were inactivated by polymerizing actin. These data show, for the first time, that small G proteins can regulate Na+channels, and an intracellular mechanism mediating their effect involves actin cytoskeleton rearrangements. © 2003 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.
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