Figure 5. The Kv7/M channel enhancer retigabine potentiates.

I_m more in juvenile than in neonatal neurons Examples of deactivating currents recorded from a P1 (upper traces, Neonates) and from a P18 (lower traces, Juveniles) CA3 principal cell. The deactivation protocol (represented below the current traces) consisted in stepping the voltage from −20 mV down to −100 mV in increments of 10 mV, before (Control) and during bath application of 10 μm retigabine (Retigabine). On the right, retigabine-sensitive currents obtained by subtracting the currents recorded in the presence of retigabine from control (Difference). The horizontal dotted lines mark the I_m reversal potential. B, each column represents the density (pA pF⁻¹) of retigabine-sensitive currents (for voltage steps from −20 to −100 mV) normalized to the cell capacitances in neonatal (n = 5) and in juvenile neurons (n = 5). *P < 0.05. C, voltage dependence of deactivated retigabine-sensitive currents (normalized to the maximal currents obtained at +10 mV) obtained in neonatal (filled symbols) and juvenile neurons (open symbols). Continuous lines represent the Boltzmann fits of experimental data (each point is the average of 4–5 individual values). The V_1/2 values were −16.6 ± 6.0 mV and −39.8 ± 4 mV for neonatal and juvenile neurons, respectively. These values were significantly different (P < 0.05). The corresponding slope factors were 21.4 ± 6.4 and 24.5 ± 3.2.