Objective To evaluate the role of ATP-sensitive potassium (KATP) channel in spinal dorsal horn neurons in hyperalgesia after thoracotomy in rats.Methods Twenty-eight Sprague-Dawley rats,aged 7-9 weeks,weighing 250-350 g,in which intrathecal catheters were successfully implanted without complications on 14th day after chronic post-thoracotomy pain was induced,were randomly divided into 4 groups (n =7 each):control group,the solvent dimethyl sulfoxide (DMSO) group,KATP channel opener pinacidil group (group P) and KATP channel blocker glibenclamide group (group G).10％ DMSO 10 μl,pinacidil 10 μg/10 μl and glibenclamide 50μg/10μ1 were injected intrathecally in groups DMSO,P and G at 5 day after the intrathecal catheter was implanted,respectively.Paw withdrawal threshold to von Frey filament stimulation was measured before intrathecal administration and at 10,30 and 60 min after intrathecal administration and the acetone test was performed.Coldinduced pain threshold was measured.Results There was no significant difference in paw withdrawal threshold to yon Frey filament stimulation at each time point among the four groups (P ＞ 0.05).Compared with C and DMSO groups,cold-induced pain threshold was significantly increased in group P and decreased in group G (P ＜ 0.05).There was no significant difference in cold-induced pain threshold between C and DMSO groups (P ＞ 0.05).Conclusion KATP channel in spinal dorsal horn neurons is involved in the maintenance of hyperalgesia after thoracotomy in rats.