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目的 研究脑内神经递质去甲肾上腺素 (NE)、肾上腺素 (E)与异氟醚MAC之间的关系。方法 18只成年雄性大鼠吸入异氟醚 ,浓度分别为 0 6 %、0 8%、1 0 %、1 2 %及 1 4% ,脑皮层内插入 0 0 5mm内径的微透析探针 ,用人工脑脊液灌注 ,收集透析液 ,监测定量脑电图 ,测定MAC及角膜反射消失时NE及E的浓度后 ,将大鼠随机分为三组 ,A组 :尾静脉缓慢注射 (>2min)可乐定 0 2mg/kg+持续泵注 0 15mg kg-1·h-1;B组 :可乐定 0 2mg kg-1·h-1加入人工脑脊液中持续脑皮层内灌注 ,流量 2 μl/min ;C组 :盐水对照组 ,尾静脉缓慢 (>2min)注射生理盐水 1ml +持续泵注 0 8ml/min维持 ,2 0min后 ,再测MAC ,监测定量脑电图 ,用高压液相电化学检测器分析脑组织微透析液中NE及E的浓度。结果 异氟醚吸入浓度与NE浓度呈正相关 (r =0 995 ,P <0 0 1) ,与E浓度呈负相关 (r =-0 981,P <0 0 5 )。疼痛消失时的E浓度明显低于角膜反射消失时的浓度 (P <0 0 5 ) ,而NE浓度无显著性差异 (P >0 0 5 )。静脉注射可乐定后异氟醚MAC显著性降低 (P <0 0 1) ,NE浓度也稍降低 (P <0 0 5 ) ;脑皮层内局部灌注可乐定不影响MAC、NE及E的水平 (P >0 0 5 )。静注可乐定后EEG97%谱边界频率 (97%SEF)及中位频率 (MPF)降低 (P <0 0 5 )
Objective To study the relationship between intracerebral neurotransmitters norepinephrine (NE), epinephrine (E) and isoflurane MAC. Methods Twenty-eight adult male rats were inoculated with isoflurane at concentrations of 0 6%, 0 8%, 10%, 12% and 14% respectively. Micro-dialysis probes of 0 0 5 mm ID were inserted into the cortex. After artificial cerebrospinal fluid perfusion, dialysate collection, quantitative electroencephalogram monitoring, NE and E concentrations at MAC and corneal reflex disappearance, the rats were randomly divided into three groups: group A: slow injection (> 2 min) of clonidine Group B: clonidine 0 2mg kg-1 · h-1 added into the artificial cerebrospinal fluid in the cerebral cortex perfusion, the flow rate of 2 μ l / min; Group C: 0-2mg / kg + continuous infusion of 0 15mg kg-1 · h- Saline control group, tail vein slowly (> 2min) injection of normal saline 1ml + continuous pump 0 8ml / min to maintain, 20min, retest MAC, quantitative electroencephalogram monitoring, high pressure liquid phase electrochemical detector brain tissue Concentrations of NE and E in microdialysate. Results The inhaled concentration of isoflurane was positively correlated with the concentration of NE (r = 0 995, P 0 01) and negatively correlated with the concentration of E (r 0 981, P 0 05). The concentration of E at the time when pain disappeared was significantly lower than that at the time when corneal reflex disappeared (P <0 05), while the NE concentration was not significantly different (P 0 05). Intravenous clonidine decreased the isoflurane MAC significantly (P <0.01) and the NE concentration also slightly decreased (P <0.05). Local cerebral perfusion of clonidine did not affect the levels of MAC, NE and E P> 0 0 5). After intravenous clonidine, EEG97% spectral boundary frequency (97% SEF) and median frequency (MPF) decreased (P <0 05)