AIM: To investigate the antinociceptive effect of anticholinesterase agent physostigmine at different postoperative time, and the interaction of intravenous physostigmine with intrathecal morphine in rats. METHODS: Six groups of rats were operated on for intrathecal and intravenous catheterization. Nociceptive responses of hind paws of each animal were measured with "plantar stimulation" test 1-3 h and 3 d postoperatively. Animals received intravenous (iv) physostigmine, intrathecal (ith) morphine, or combination of both. The antinociceptive effect of each group was converted to the percent maximum possible effect (% MPE). RESULTS: Administration of physostigmine 1-3 h after operation resulted in dramatic increase in % MPE. The effects of combinations of iv physostigmine and ith morphine were more pronounced at early postoperative time. The potency of low dose combination was significantly greater than that of double doses of both drugs. The % MPE of the observed effects of all combinations was significantly higher than that of the expected additive effects. CONCLUSION: The antinociception of physostigmine occurs at early postoperative time. The interaction of iv physostigmine with ith morphine indicates their synergistic effect.%目的:观察在术后不同阶段静脉注射胆碱酯酶抑制剂毒扁豆碱对鼠痛阈的影响,以及静注毒扁豆碱和蛛网膜下腔注射吗啡的药物相互作用.方法:6组SD大鼠,置入蛛网膜下腔和股静脉导管.采用辐射热刺激诱发的鼠腿撤退试验测痛阈,测试分别于术后1～3 h和术后3 d进行.动物分别接受静注毒扁豆碱、蛛网膜下腔注射吗啡及两者联合给药.比较术后1～3 h和3 d各种药物对痛阈的影响、联合给药与单独给药对痛阈的影响.药物的镇痛效应以最大可能效应的百分比(%MPE)表示.结果:毒扁豆碱术后1～3 h静注导致%MPE明显提高;毒扁豆碱与吗啡的联合给药效应在术后早期更明显;小剂量联合给药的镇痛作用明显大于双倍剂量单独给药的镇痛作用;联合给药的测得效应值明显大于估计叠加效应值.结论:胆碱酯酶抑制剂毒扁豆碱在术后早期产生镇痛作用;静注毒扁豆碱与蛛网膜下腔注射吗啡的联合给药呈协同效应.
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