The effect of tetramethylammonium on single sodium channel currents.
Voltage-dependent Na conductance of rat myotubes was studied by patch recordings of single-channels. The patches were excised from the cell with the patch electrode, and the cytoplasmic surface was bathed in either CsF or tetramethylammonium (TMA)-F. Inward currents were examined from -20 to -50 mV. In this range Cs and TMA both appeared to be nearly impermeant, but TMA blocked the channel in a voltage-dependent manner. A first-order blocking site was located a maximum of 89% of the way through the membrane field from the cytoplasmic surface.
D000818:Animals; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology*
D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D012964:Sodium