The relaxation of ions can contribute additional "state" during gating current measurement.

Abstract

A transient time is needed for a potential step to travel through the solution between the metal electrode and the membrane. The effects of the double layer that exists at the electrode-solution interface may cause a delay for the signal reaching the surface of the membrane to initiate any voltage dependent reaction. The process by which the ions of the solution redistribute themselves is described by a relaxation model. The relaxation time is related to the resistance of the solution and the equivalent capacitance of the diffuse double layer. The theory is then applied to the experiments that measured the gating process of nerve membrane. The delay time of the rise in the sodium conductance on polarization is calculated for various polarized potentials and holding potentials and the numerical results can explain the experimental data without using the multi-state kinetic models. It indicates that the relaxation time of the solution should be taken into consideration for any membrane experiment with time courses of similar order.