Incomplete inactivation of sodium currents in nonperfused squid axon

Perfused squid axons in which K-conductance is blocked show, under voltage clamp, incomplete inactivation of the sodium conductance. The presence of this phenomenon in nonperfused axons was found by comparing membrane current records before and after tetrodotoxin addition to the bathing solution. Sodium currents in nonperfused axons are comparable in behavior at positive potentials to those seen in Cs-perfused axons.