1997 Fiscal Year Final Research Report Summary
The electrophysiological studies in the action of xenon on the central nervous system
| Project/Area Number |
08457406
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | Fukushima Medical College (1997)
Kyoto University (1996) |
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Principal Investigator |
MURAKAWA Masahiro Fukushima Medical College, Professor, 医学部, 教授 (90182112)
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| Co-Investigator(Kenkyū-buntansha) |
ADACHI Takehiko Kyoto Univ.Faculty of Medicine, Lecturer, 医学研究科, 講師 (90252428)
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| Project Period (FY) |
1996 – 1997
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| Keywords | xenon / nitrous oxide / somatosensory evoked potentials / electroencephalogram / multi-unit activity / wide dynamic range neuron / 広作動域ニューロン |
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| Research Abstract |
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.
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