Fig. 5.

Properties of the slowly inactivating axonal outward current. (A) Axonal voltage steps from a holding potential of −95 mV. (B) Hyperpolarizing steps from a holding potential of −5 mV. (C) Construction of activation and inactivation curves for the slowly inactivating component (n = 9; average recording distance: 99±37 μm). (D) Removal of inactivation after steps to −60, −80, and −100 mV for varying lengths of time (axonal recording 300 μm from the soma). (E) Time course of normalized removal of inactivation data (n = 8; normalized to the tail current after a 5-sec step to −130 mV). Two time courses of removal of inactivation are found, with average time constants of 6.7 and 0.26 sec (average axonal recording distance: 224 ±55 μm). (F) The time constant of the fast component becomes slower with depolarization. (G) The contributions of the faster (first) and slower (second) components varied with voltage.