The components of membrane conductance in the giant axon of Loligo

The flow of current associated with depolarizations of the giant axon of Loligo has been described in two previous papers (Hodgkin, Huxley & Katz, 1952; Hodgkin & Huxley, 1952). These experiments were concerned with the effect of sudden displacements of the membrane potential from its resting level (V=0) to a new level (V = Vj). This paper describes the converse situation in which the membrane potential is suddenly restored from V = V1 to V = 0. It also deals with certain aspects of the more general case in which V is changed suddenly from V1 to a new value V2. The experiments may be conveniently divided into those in which the period of depolarization is brief compared to the time scale of the nerve and those in which it is relatively long. The first group is largely concerned with movements of sodium ions and the second with movements of potassium ions. METHODS The apparatus and method were similar to those described by Hodgkin et al. (1952). The only new technique employed was that on some occasions two pulses, beginning at the same moment but