Theoretical implication of liganding reactions in axonal sodium channel gating.
Mathematical simulation models for measured permeability properties of axonal Na(+) channels point to the presence of bimolecular, as well as net-membrane-field-dependent intramolecular, reaction steps in channel gating reactions. An abstract chemical reaction model is presented, which postulates ligand binding reactions in both Na(+) channel activation and subsequent desensitization as observed in voltage-clamp experiments. Membrane capacitance currents due to the movement of charged or dipolar gating structures also indicate that the early phase of the gating charge movement is dictated by local, rather than net-membrane-field-driven reactions, and therefore reflect energy input from chemical sources which are an integral part of the membrane.
Dorogi
P L
PL
Max-Planck-Institut für Biochemie D-8033 Martinsried/München, FRG.
Neumann
E
E