Central nervous system effect of enflurane.

实验在猫和大鼠身上进行。在安氟醚(2-5%)麻醉的猫，低碳酸血症(PaCO_2；20 mm Hg)不能诱发脑电发作，而刺激(敲击前肢)则在常压状态下或在安氟醚浓度高于3.5%时诱发低碳酸血症。诱导癫痫发作所需的刺激呈剂量依赖性减少。单侧大脑皮质切除对丘脑脑电无明显影响。皮质脑电也不受丘脑和海马腹基底复合体(VB)破坏的影响。诱导癫痫发作所需的刺激不受海马体破坏的影响，但被VB破坏而增加。在安氟醚麻醉过程中，电刺激坐骨神经引起的皮层和丘脑的体感诱发电位呈剂量依赖性地抑制，而皮质切除不影响。另一方面，安氟醚提高了电诱导癫痫的阈值，并呈剂量依赖性地抑制TH…药物(戊四氮、海人酸、青霉素)致痫较多。此外，深安氟醚麻醉可消除皮质内注射青霉素引起的大鼠VB、大脑皮层、穹窿体区和内囊葡萄糖消耗的增加，而4%安氟醚对这些区域的葡萄糖消耗有明显的升高作用。在猫，即使在前肢敲击诱发癫痫发作时，也没有观察到胼胝体和海马CA3区葡萄糖消耗量的增加。4%安氟醚麻醉时局部脑血流量显著增加，低碳酸血症使局部脑血流量减少，可能导致代谢和血流的解偶联。综上所述，躯体感觉刺激在深安氟醚麻醉时诱导癫痫发作，而电或药物诱导的癫痫发作被抑制，提示安氟醚具有致痫和抗癫痫作用。结果还表明，在安氟醚麻醉期间，大脑皮层和皮质间的活动存在物种差异。较少

Experiments were performed in cats and rats. In cats anesthetized with enflurane(2-5%), eeg seizures were not induced by hypocapnia(PaCO2;20mmHg), while with stimulation(tapping forelimb), seizures were induced either at normocapnia or hypocapnia when enflurane was above 3.5%. The stimulation required to induce seizures was dose-dependently decreased. Unilateral excision of cerebral cortex did not change EEG in the thalamus. Cortical EEG was not also affected by a destruction of ventrobasal complex(VB) in the thalamus and of the hippocampus. Stimulation required to induce seizures was not affected by a hippocampal destruction but was increased by a VB destruction. Somatosensory evoked petentials in the cortex and thalamus by an electrical stimulation of sciatic nerve during enflurane anesthesia were dose-dependently suppressed, and were not affected by cortical excision.Enflurane, on the other hand, increased threshold of electrically induced seizures and dose-dependently suppressed th … More e seizures induced by drugs (pentylenetetrazol, kainic acid, penicillin). Furthermore, deep enflurane anesthesia abolished the increase of glucose consumption in the VB, cerebral cortex, corpus callosum and internal capsule produced by intracortical injection of penicillin despite enflurane(4%) alone produced characteristic increase in these areas in rats. The increase in glucose consumption in the corpus callosum and hippocampal CA3 was not observed in cats even when seizures were induced by forelimb tapping. Local cerebral blood flow was markedly increased during 4% enflurane anesthesia, which was decreased by hypocapnia, possibly producing uncoupling between metabolism and flow.In summary, somatosensory stimulation induces seizures during deep enflurane anesthesia, while electrically or drug-induced seizures are suppressed, suggesting epileptogenic and antiepileptic properties of enflurane. The results also demonstrated the species difference in cerebral cortical and intercortical activities during enflurane anesthesia. Less