Figure 3. Intravenous administration of lidocaine decreases the frequency of spontaneous EPSCs but not change their amplitude.

(a) Intravenous lidocaine (10 mg/kg) decreases the frequency of spontaneous excitatory postsynaptic currents (EPSCs). In contrast, it has no effect on the spontaneous EPSC amplitude. Downward arrows indicate outtakes of the top trace shown on an expanded timescale. Lidocaine was administered for 3 min from the arrowhead. (b) Intravenous lidocaine (3 mg/kg) decreases the frequency, but not the amplitude, of spontaneous EPSCs. In contrast, intravenous lidocaine (1 mg/kg) has no effect on the spontaneous EPSC frequency or amplitude. (c) Average frequency (upper graph) and amplitude (lower graph) of spontaneous EPSCs in the presence of lidocaine (10, 3, 1 mg/kg) relative to controls are shown as a function of time (mean ± standard error of the mean, n = 12, 9, 7, respectively). (d) Intravenous lidocaine (10 mg/kg) significantly shifts the cumulative distribution of the inter-event intervals to the right (P < 0.01, Kolmogorov-Smirnov test) (upper graph). In contrast, it has no effect on the cumulative distribution of the amplitudes (P = 0.11) (lower graph).