L—硝基精氨酸在大鼠经脊髓作用预防局麻药坐骨神经阻滞的耐药反应

目的：阐明一氧化氮在脊髓阶段预防局麻药坐骨神经阻滞耐药反应的作用。方法：大鼠随机分为3组。第一组NS腹腔内和蛛网膜下腔注射。第二组NS腹腔内和L－NAME蛛网膜下腔注射。第三组NS蛛网膜下腔和L－NAME腹腔内注射。L－NAME腹腔内或蛛网膜下腔注射的剂量是1，10，100，1000，10000nmol（n=9／组）。随后用3％二氯普鲁卡因0．3mL依次3次阻滞坐骨神经，记录每次热痛觉、本体感觉和运动功能阻滞持续时间。结果：L－硝基精氨酸局麻药坐骨神经阻滞耐药反应的蛛网膜下腔的50％有效剂量显著地低于腹腔内注射的50％有效剂量，比率至少超过20倍。结论：L－硝基精氨酸通过脊髓作用预防局麻药耐药反应。

Effects of L-NAME at Spinal Level in Preventing Tachyphylaxis of Sciatic NerveBlock to Local Anesthetic in Rats

Objective:To elucidate the role of nitric oxide at spinal level in preventing the tachyphylaxis of sciatic nerve block to local anesthetic.Methods:Rats were randomly divided into 3 groups.Group 1 received saline intraperitoneally and intrathecally.Group 2 had saline intraperitoneally and a nitric oxide synthesis inhibitor L_nitroso_arginine methyl ester (L_NAME) intrathecally.Group 3 was treated with saline intrathecally and L_NAME intraperitoneally.L_NAME was injected at doses of 1,10,100,1 000 and 10 000 nmoL ( n =9/group).Thereafter three sequential sciatic nerve blocks were performed with 0 3mL of 3% 2_chloroprocaine.Durations of block of thermal nociceptive,proprioceptive and motor responses were recorded after each blockage.Results:The ED50s of L_NAME for prevention of tachyphylaxis of sciatic nerve block to local anesthetic were significantly lower for intrathecal injection in comparison with intraperitoneal injection.The ED50s ratios were more than 20 times.Conclusion:These results indicate that L_NAME prevents the tachyphylaxis to local anesthetic block via a spinal action.