title: Evidence for existence of two acid groups controlling the conductance of sodium channel.
abstract: The inhibition of the sodium current in nodal membrane at low pH external solutions was studied under voltage clamp conditions. Analysis of the data for membrane potentials from +10 to +150 mV shows that the inhibition of the Na+ currents at high positive potentials cannot be described by a titration curve of a single acid group. The data can be explained on assumption that the conductance of each sodium channel is controlled by two acid groups: one is located within the pore, the other just near the outer mouth of the pore. The affinity of both groups for H+ is estimated.
mesh_terms: D000818:Animals; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials; D009186:Myelin Sheath / Q000502:physiology*; D011895:Rana ridibunda; D012964:Sodium / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D012964:Sodium