Fig. 10.

Modulation of the M current by retigabine is concentration dependent. A, Superimposed M-current traces before and after cumulative addition of retigabine (0.1–30 μm). The M current was recorded in response to 1 sec hyperpolarizing steps from a holding potential of −20 to −50 mV followed by a ramp to −90 mV. Note that the increase in holding current is associated with alteration of M-current deactivation relaxation. B, Holding current at −50 and −20 mV plotted against retigabine concentrations for the cell illustrated inA. Solid lines represent best fits to the Hill equation with holding currents in the absence of retigabine of 610 pA at −20 mV and 42 pA at −50 mV (as indicated byarrows). EC₅₀ values and Hill coefficient (slope) are indicated. Mean values are given in Results.