Figure 1.

Prepulse potentiation of Kv1.2 channels. A, Whole-cell patch-clamp recordings of Kv1.2 channels expressed in LM cells. Recordings are representative of currents elicited from cells exhibiting a fast gating phenotype with no prepulse potentiation (bottom) and a slow gating phenotype (top) in which activation of channels during a prepulse causes accelerated activation in a second pulse. B, Conductance–voltage relationships elicited before and after a 500 ms potentiating prepulse to 60 mV (protocol depicted in sample currents in C) in cells that exhibit either slow mode or fast mode gating. Cells with prominent slow mode gating (red symbols) exhibit a marked leftward shift of the V_1/2 of activation after potentiation. C, Activation curves of nonpotentiated and potentiated channels were measured by pulsing cells in 10 mV steps between −70 and 70 mV in two families of sweeps (P1, P2), separated by a pulse to 60 mV. Currents from a representative cell exhibiting the slow gating phenotype are highlighted in red, and a cell exhibiting the fast gating phenotype is in blue (sweeps with test pulses to −30 mV are bolded). Activation kinetics are plotted against the shift in activation V_1/2 measured between the P1 and P2 families of sweeps.