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Updated: Aug 14, 2026

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes
Published on: January 10, 2011
Modulation of the voltage-dependent sodium channel by agents affecting G-proteins: a study in Xenopus oocytes
M Cohen-Armon1, M Sokolovsky, N Dascal
1Department of Biochemistry, George S. Wise Institute of Life Sciences, Ramat Aviv, Israel.
Abstract:
The effects of agents known to affect G-proteins on voltage-dependent, tetrodotoxin-sensitive Na+ channels were studied in Xenopus oocytes injected with rat brain RNA, using two-electrode voltage-clamp technique. The non-hydrolysable analogue of GTP, GTP-gamma-S, known to activate G-proteins, inhibited the Na+ current (INa). The decrease in the amplitude of INa was not accompanied by changes in activation or inactivation characteristics of the channel. The non-hydrolysable analogue of GDP, GDP-beta-S, had no effect on INa. The responses to gamma-aminobutyric acid and kainate in the same oocytes were also attenuated by GTP-gamma-S. Pertussis toxin, which inactivates some G-proteins by catalyzing their ADP-ribosylation, enhanced INa, but did not prevent the inhibition of INa by GTP-gamma-S. We conclude that the Na+ channel, and possibly the GABA and kainate receptors and/or channels, are coupled to a G-protein. The activation of the G-protein modulates the channels either directly, or via activation of biochemical cascade possibly involving production of second messengers and channel phosphorylation.
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