右美托咪定对氯胺酮镇痛及催眠的增强作用

目的探讨右美托咪定(DMM)对氯胺酮(Ket)镇痛及催眠作用的影响。方法采用热板法观察DMM 10μg.kg-1对Ket 25 mg.kg-1热板痛阈(HPPT),扭体法观察DMM 5μg.kg-1对Ket 25 mg.kg-1扭体次数的影响;翻正反射法观察DMM 40μg.kg-1对Ket 100 mg.kg-1翻正反射消失持续时间的影响。结果热板法实验中,与正常对照组相比,单独给DMM在5～15 min HPPT明显延长(P<0.05,P<0.01),Ket麻醉组在5 min HPPT明显延长(P<0.01)。与Ket麻醉组相比,合用DMM组,HPPT增加更明显(P<0.05,P<0.01)。与DMM+Ket合用组相比,DMM+阿替美唑(Ati)+Ket合用组HPPT明显降低(P<0.05,P<0.01),且与Ket麻醉组相当,10 min后与正常对照组接近。扭体法实验中,与正常对照组相比,单用DMM组及Ket麻醉组的扭体次数明显减少(P<0.01);两者合用后,扭体次数减少更明显,与Ket麻醉组相比有显著差异(P<0.01)。与DMM+Ket组相比,DMM+Ati+Ket组的扭体次数明显增加(P<0.01),且与单用DMM组和Ket麻醉组相当,但依旧明显低于正常对照组(P<0.01)。翻正反射法实验中,与Ket麻醉组相比,DMM+Ket合用组的翻正反射消失持续时间明显延长(P<0.01)。与DMM+Ket合用组相比,DMM+Ati+Ket合用组的翻正反射消失持续时间明显缩短(P<0.01),且与Ket麻醉组接近。结论合用右美托咪定,氯胺酮的镇痛及催眠作用增强,而α2受体可能是该效应的主要受体机制之一。

Enhancement of dexmedetomidine on analgesic and hypnotic effects of ketamine

OBJECTIVE To explore effects of dexmedetomidine(DMM) on analgesic and hypnotic effects of ketamine(Ket). METHODS Effect of DMM 10 μg·kg^-1 on hot plate pain threshold (HPPT) of Ket 25 mg·kg^-1 was detected by hot-plate test. Effect of DMM 5 μg·kg^-1 on writhing times of Ket 25 mg·kg^-1 was detected by writhing test and effect of DMM 40 μg·kg^-1 on the duration of righting reflex disappearance of Ket 100 mg·kg^-1 was detected by hypnotic test. RESULTS In hot- plate test, compared with normal control group, HPPT was significantly prolonged within 5-15 min when given DMM alone(P<0.05, P<0.01), and HPPT was significantly prolonged at 5 min when given Ket alone(P<0.01). Compared with Ket group, HPPT significantly increased in DMM+Ket group(P<0.05, P<0.01). Compared with DMM+Ket group, HPPT significantly decreased in DMM+atipamezole(Ati)+Ket group (P<0.05, P<0.01) and was similar with Ket group. In writhing test, compared with normal control group, writhing times significantly decreased in DMM group and Ket group(P<0.01), and the writhing times more significantly decreased in Ket+DMM group (P<0.01). Compared with DMM+Ket group, the writhing times increased significantly in DMM+Ati+Ket group (P<0.01) and was similar with DMM group or Ket group, but it still was lower than normal control group(P<0.01). In hypnotic test, compared with Ket group, the duration of righting reflex disappearance was significantly prolonged (P<0.01) in DMM+Ket group. Compared with DMM+Ket group, the duration of righting reflex disappearance was significantly shortened (P<0.01) and was similar with Ket group in DMM+Ati+Ket group. CONCLUSION The analgesic and hypnotic effects of Ket are enhanced combined with DMM, and the alpha 2 receptor may be one of the major receptors in their mechanisms.