Figure 3

Effect of short-term (60 min) remifentanil infusions on thermal thresholds measured by plantar test. (A) Time course. The withdrawal latencies increased in a dose-dependent manner. During the infusion, all of the withdrawal latencies were significantly different from the baseline values except at 15 min with an infusion rate of 120 mg/kg/h. (B) A comparison of the withdrawal latencies at each time point. At 60 min, the maximum analgesia was reached with all of the infusion rates. The withdrawal latencies at rates of 120 and 180 mg/kg/h were not significantly different from the latency induced by 240 mg/kg/h at 60 min. The data are expressed as the mean ± SEM; n = 8 mice for all of the groups. *P < 0.05 vs. baseline; ^#P < 0.01, ^##P < 0.05 vs. 240 mg/kg/h (one-way ANOVA followed by Dunnett’s test).