A Calculation of the Current Voltage Characteristic of a Voltage-Controlled Model Membrane Ion Channel

A simple calculation is made of the current-voltage characteristic of a model ion channel in which the ion transfer rate is controlled by an electrical potential gradient rather than by mechanical gating particles. Although the model deals with sodium and potassium channels similarly, very different characteristics are obtained that approximate to those measured in the squid giant axon. The difference is due essentially to the very different Nernst potentials for these two ions. The ability of the model to predict channel activation due to both depolarization and hyperpolarizing voltage transients is described.