Figure 1. Brief depolarizing conditioning prepulses do not alter the activation properties of L-currents elicited by subsequent depolarization.

Representative traces in the absence of (A) and following a conditioning prepulse (B) consisting of a 200 ms depolarization to +40 mV and a 25 ms repolarization to -50 mV (to allow for complete L-channel deactivation). The effect of the prepulse was studied for test pulses from -50 to +70 mV in 10 mV increments (V_test). Insets, representative L-currents elicited at +40 mV were fitted according to a second-order exponential function (□, superimposed over the data), as described in Methods. C, I-V relationships of L-currents elicited in the absence of (•) and following (○) the conditioning protocol. Currents are normalized to the peak current (30 mV) in each test pulse. D, the fast (τ_fast, circles) and slow (τ_slow, squares) time constants for L-currents elicited in the absence (filled symbols) or presence (open symbols) of a conditioning prepulse are plotted for test potentials between 20 and 50 mV (*P < 0.01). E, the fractional contribution of the fast (A_fast/A_total, circles) and slow (A_slow/A_total, squares) components of the total L-current elicited in the absence (filled symbols) or presence (open symbols) of the conditioning prepulse are plotted for test potentials between 20 and 50 mV.