title: Solvent substitution as a probe of channel gating in Myxicola. Effects of D2O on kinetic properties of drugs that occlude channels.
abstract: The effects of solvent substitution on the steady-state and kinetic properties of drugs (gallamine triethiodide) and ions (nonyltriethylammonium and Ba++) known to occlude Na+ and K+ channels have been examined and compared with the effects of D2O on unmodified channels. In general, we observed large isotope effects on the kinetics of occlusion at temperatures of 5 degrees C, but only minor effects at 15 degrees C, consistent with processes involving significant solvent interaction. Steady-state behavior was not affected. In the case of gallamine, where a dual effect on INa is evident, although both processes were D2O sensitive, only the occlusion phase had a significant temperature dependence.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D001464:Barium / Q000494:pharmacology; D003903:Deuterium / Q000494:pharmacology*; D004558:Electric Stimulation; D005703:Gallamine Triethiodide / Q000494:pharmacology; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials; D011077:Polychaeta; D011188:Potassium / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013696:Temperature
chemical_list: D007473:Ion Channels; D000644:Quaternary Ammonium Compounds; D001464:Barium; C033910:nonyltriethylammonium; D012964:Sodium; D003903:Deuterium; D005703:Gallamine Triethiodide; D011188:Potassium