[Selectivity and sensitivity to blocking by hydrogen ions of batrachotoxin-modified sodium channels in nerve fiber membranes].
Currents through normal and batrachotoxin-modified sodium channels in frog nerve were measured under voltage clamp conditions. Measured reversal potentials and the Goldman equation were used to calculate relative permeabilities. The permeability ratios were: PNa: PNH4: PK = 1: 0.47: 0.19. Hydrogen-to-sodium permeability ratio was estimated from reversal potential measurements in Na-free acid (pH 3.7-3.8) solutions. It was 528 +/- 46 for batrachotoxin-modified sodium channels. Modified channels were less sensitive to hydrogen block as compared with normal ones. The difference in apparent pKa for acid group between normal and modified channels was about 0.40.
D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001496:Batrachotoxins / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D006859:Hydrogen / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008564:Membrane Potentials; D009413:Nerve Fibers, Myelinated / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism; D011895:Rana ridibunda; D012964:Sodium / Q000378:metabolism*
D001496:Batrachotoxins; D007473:Ion Channels; D000641:Ammonia; D006859:Hydrogen; D012964:Sodium; D011188:Potassium
Selektivnost' i chuvstvitel'nost' k blokirovaniiu ionami vodoroda modifitsirovannykh batrakhotoksinom natrievykh kanalov v membrane nervnogo volokna.