Fig. 2
a-b The NMDA antagonist ketamine and MgSO4 were administered intrathecally 30 min before remifentanil infusion and surgical incision. Paw withdrawal mechanical threshold (a) and paw withdrawal thermal latency (b) were evaluated at 24 h before incision and 2, 6, 24, 48, 72 h, 7 days after remifentanil infusion, 6 h after re-exposure of remifentanil 7 days later. Groups allocation: RI: Group remifentanil + surgical incision; C: Group Control; RIK: Group i.t. 10 μg ketamine was given to the group RI; RIMlow: Group i.t. 100 μg MgSO4 was given to the group RI; RIMhigh: Group i.t. 300 μg MgSO4 was given to the group RI. Data are expressed as means ± SD. * P < 0.001 compared with Group C, # P < 0.001 compared with Group RI, + P < 0.01 compared with Group RIMlow, ΔP < 0.05 compared with Group RIMhigh