Reactance of biological membranes

Discusses the reactance of a voltage-gated channel that obeys first-order kinetics, where the current-voltage characteristic is derived and linearized at an arbitrary quiescent point. It is shown that the reactance is inductive in the high-conductance region of the characteristic, where the incremental conductance is larger than the chord conductance; that the reactance is capacitive in the low-conduciance region, where the incremental conductance is smaller than the chord conductance; and that the reactance vanishes at the equilibrium potential. The values of the elements of the equivalent circuit are derived as a function of membrane voltage and parameters, and some general aspects of the reactance of biological membranes are discussed.