Fig. 4.
Kinetics and voltage dependence ofIA. A, Steady-state inactivation curve. The inset represents a series of current traces from an isolated bouton, produced by a test potential to 50 mV after prepulses to a range of membrane potentials between −120 and −10 mV (no leak subtraction was applied). The graph includes pooled data from seven different boutons. Peak amplitudes ofIA were normalized and plotted as a function of the prepulse potential, and the data were fitted with a Boltzmann function with half-inactivation of 62 mV and a slope factor of 13 mV.B, Time course of recovery from inactivation. Complete inactivation of IA was produced by a test command to 50 mV from a holding potential of −100 mV. Recovery from inactivation was tested by returning the membrane potential to −100 mV for a progressively longer time before a second test pulse was applied.