Fig. 7 . Analysis of the K⁺ conductance (gK) and Na⁺ conductance (gNa) during a membrane action potential. All recordings were made at 10°C. The holding potential before current-clamp was -65 mV. Axons were bathed in 10K ASW (see Materials and methods). , L. pealei; , L. plei; , Sepioteuthis sepioidea. Values are means ± S.E.M. For all data, the action potential peak is considered to be time zero, and all time measurements are shifted accordingly. For gK experiments, data points are at 50 µs intervals for L. pealei and at 200 µs intervals for L. plei and S. sepioidea. For gNa, time points are at 20 µs intervals for L. pealei and at 50 µs intervals for L. plei and S. sepioidea. (A) Time course of gNa (per surface area) versus time. N=5 for all species. (B) gNa normalized to peak values versus time (same data as in A). (C) Time course of gK (per surface area) versus time. N=4 for all species. (D) gK normalized to peak values versus time (same data as in C).