title: Hydrogen ion block of the sodium pore in squid giant axons.
abstract: The block of squid axon sodium channels by H ions was studied using voltage-clamp and internal perfusion techniques. An increase in the concentration of internal permeant ions decreased the block produced by external H ions. The voltage dependence of the block was found to be nonmonotonic: it was reduced by both large positive and large negative potentials. The ability of internal ions to modify the block by external H+ is explained by a competition among these ions for a binding site within the pore. The nonmonotonic voltage dependence is consistent with this picture if the hydrogen ions are allowed to be permeant.
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D001665:Binding Sites; D049832:Decapodiformes; D003864:Depression, Chemical; D006859:Hydrogen / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D008954:Models, Biological
chemical_list: D007473:Ion Channels; D006859:Hydrogen