The electrophysiological studies in the action of xenon on the central nervous system

我们比较了氙气（Xe）和氧化亚氮（N2O）对中枢神经系统电活动的影响。我们记录了猫的脑电图（EEG）、中脑网状结构多单元活动（R-MUA）和体感诱发电位（SEP）。采用2%和5%七氟醚基础麻醉。当七氟醚浓度为2%时，70% Xe最初产生有节奏的慢波，随后在脑电图上出现高振幅锐波的爆发，中间被低振幅慢波打断。Xe诱导R-MUA初始升高，随后降低。n2070%降低脑电图活动幅度，这与R-MUA增加有关。与N2O相比，Xe对SEP初始正负偏转幅度的抑制作用更大。在5%七氟醚麻醉下，两种麻醉剂都增加了脑电图峰值的频率，促进了R-MUA。我们还评估了这两种麻醉药的效力，通过抑制皮肤有害（夹）刺激引起的脊髓宽动态范围神经元对被氯蔗糖和氨基甲酸乙酯麻醉的猫后肢的反应。吸入70% Xe时，11个神经元中有7个对捏刺激的反应被抑制。N2O 70%抑制了11个神经元中的8个。比较了Xe和N2O在被两种麻醉药抑制的6个神经元中的效力。吸入Xe 20min后，按压反应被抑制至49.5%，而氧含量为70%的N2O将按压反应抑制至45.9%。N2O和Xe之间的差异不显著。这些结果表明，Xe对脑背景活动的刺激作用和对脑反应能力的抑制作用比N2O更强；Xe和N2O对脊髓背角神经元的抑制程度相似。

We have compared the effects of xenon (Xe) and nitrous oxide (N2O) on central nervous system electrical activity. We recorded the electroencephalogram (EEG), multi-unit activity of midbrain reticular formation (R-MUA) and somatosensory evoked potentials (SEP) in cats. Basal anesthesia with 2% and 5% sevoflurane was used. With 2% sevoflurane, 70% Xe initially produced rhythmic slow waves that were followed by bursts of high-amplitude sharp waves interrupted by low amplitude slow waves on the EEG.Xe induced an initial increase, followed by a decrease in R-MUA.N20 70% decreased the amplitude of EEG activity that was associated with an increase in R-MUA.Xe suppressed the amplitude of both the initial positive and negative deflections of the SEP to a greater extent than N2O.With 5% sevoflurane anesthesia, both anesthetics increased the frequency of spikes on the EEG and facilitated R-MUA.We also assessed the potency of both anesthetics by the inhibition of the responses of wide dynamic range neuron in the spinal cord evoked by cutaneous noxious (pinch) stimulation to a hindpow in cats anesthetized with chrolarose and urethane. During 70% Xe inhalation, the responses of 7 of 11 neurons to pinch stimulation were suppressed. N2O,70%, suppressed it in 8 of 11 neurons. The potency of Xe and N2O was compared in six neurons that were suppressed by both anesthetics. After 20min of Xe inhalation, the response to pinch was suppressed to 49.5%, while N2O,70% in oxygen, suppressed it to 45.9%. The difference between N2O and Xe was not significant. These findings indicate that Xe has a stimulatory action on brain background activity and a suppressive action on brain reactive capability that is more potent than that of N2O ; Xe and N2O suppresses the spinal dorsal horn neurons to a similar degree.