Figure 1. Assessment of the behavioural response to intravenous administration of lidocaine.

(a) Intravenous lidocaine significantly increased the mechanical threshold for paw withdrawal in a dose-dependent manner. Concentrations of intravenous lidocaine ranged from 1 to 10 mg/kg. In each dose group, n = 6; **P < 0.01 in 3 mg/kg group and ^†P < 0.05 and ^††P < 0.01 in 10 mg/kg group compared to controls by one-way analysis of variance (ANOVA) with Tukey’s test, respectively. (b) Ten minutes after intravenous lidocaine administration, the mechanical threshold for paw withdrawal significantly increased in the 10 mg/kg group but not in the 3 mg/kg group. However, 30 min after lidocaine administration, the mechanical threshold significantly increased in both the 3 and 10 mg/kg groups. The mechanical threshold did not change at either time point in in the 1 mg/kg group. **P < 0.01 compared with controls by one-way ANOVA with Tukey’s test.