Effects of intrathecal or intra-cerebral ventricular midazolam on the tail flick and local cerebral and spinal metabolic responses to preripheral stimulation during isoflurane anesthesia and morphine-induced analgesia in the rat

在异氟醚麻醉或吗啡诱导镇痛的情况下，研究咪达唑仑对雄性Wistar大鼠脑室或蛛网膜下腔内异氟醚最低肺泡浓度、对有害刺激的反应、轻摇尾试验以及局部脑和脊髓葡萄糖利用的影响。异氟醚的最小肺泡浓度（MAC）为1.25%，在侧脑室给药4杯咪达唑仑后60 ~ 120 min内增加0.1%。异氟醚浓度低于MAC 0.15%时，甩尾试验（TFT）与对照组相比无显著变化，咪达唑仑可使TFT延长20 ~ 50%。当异氟醚浓度为1%时，鞘内注射咪达唑仑（20马克杯）可使尾电刺激阈值提高30-50%，从而产生逃逸反应，而咪达唑仑icv则没有改变阈值。咪达唑仑可使吗啡诱导的TFT缩短20-50%，鞘内咪达唑仑可使吗啡诱导的TFT延长30-50%。在异氟醚麻醉或吗啡诱导的镇痛下，咪达唑仑不影响局部脑或脊髓葡萄糖的利用，也不影响坐骨神经刺激引起的代谢变化。

The effects of midazolam given into the cerebral ventricle or subarachnoid space on minimum alveolar concentration of isoflurane, responses to noxious stimuli, tail flick test, and local cerebral and spinal glucose utilization with or without stimulation were examined under isoflurane anesthesia or morphic-induced analgesia in the male Wistar rats.Minimum alveolar concention (MAC) of isoflurane was 1.25%, and was increased by 0.1% from 60 to 120 min after administration of 4 mug midazolam into the lateral cerebral ventricle. At the concentration of isoflurane 0.15% less than the MAC,tail flick test (TFT) was not significantly changed compared with the control values and intra-cerebral ventricular (icv) midazolam lengthen the TFT by 20-50%. At 1% isoflurane, intrathecal midazolam (20 mug) increased the threashold of electric stimulation to the tail which produced escape responses by 30-50%, while midazolam icv did not change the thrashold.Midazolam icv shortened TFT by 20-50%, while intrathecal midazolam lengthed TFT by 30-50% under morphine-induced analgesia.Under isoflurane anesthesia or morphine-induced analgesia, midazolam icv did not influenced the local cerebral or spinal glucose utilization, nor did the metabolic changes induced by sciatic nerve stimulation.