Figure 3. I_m measured with a deactivation protocol.

A, examples of deactivation currents recorded from a P1 (upper traces, Neonates) and from a P16 (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 linopirdine (Linopirdine). On the right, linopirdine-sensitive currents obtained by subtracting the currents recorded in the presence of linopirdine from control (Difference). The horizontal dotted lines mark the I_m reversal potential. B, voltage dependence of deactivated linopirdine-sensitive currents (normalized to the maximal currents obtained at +10 mV) obtained in neonatal (filled symbols) and in juvenile neurons (open symbols). Continuous lines, representing the Boltzmann fits of experimental data (each point is the average of 5 individual values) were significantly different (P < 0.05; Wilcoxon's test). V_1/2 values were −16.5 ± 3.8 mV and −36.9 ± 5.7 mV for neonatal and juvenile neurons, respectively. The corresponding slope factors were 17.5 ± 3.2 and 16.4 ± 6.7.