1998 Fiscal Year Final Research Report Summary
CNS SUPPRESSION AND ANTICONVULSANT EFFECTS OF ANESTHETICS
| Project/Area Number |
08457415
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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 | KANSAI MEDICAL UNIVERSITY |
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Principal Investigator |
SHINGU Koh Kansai Medical University, Medicine, Professor, 医学部, 教授 (90093252)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Hideo Kansai Medical University, Medicine, Assistant, 医学部, 助手 (30247936)
TSUSHIMA Koichi Kansai Medical University, Medicine, Assistant, 医学部, 助手 (40257936)
MURAO Kohei Kansai Medical University, Medicine, Assistant, 医学部, 助手 (40247937)
TAKAHIRA Kazuyo Kansai Medical University, Medicine, Assistant, 医学部, 助手 (70174901)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Anesthetics / Epileptoid models / Anticonvulsant effects / MAC / Multiunit activity / Halothane / Isoflurane / Sevoflurane |
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| Research Abstract |
General anesthetics are required to induce unconsciousness, analgesia and suppressing reactions to stimuli during surgery. The purpose of this project is to comparing potencies in these effects between three volatile anesthetics, scvoflurane, isoflurane and halothane.
1.The spontaneous neuronal firing in the midbrain reticular formation was suppressed by all agents in dose-dependent manners, and the suppressive effects of isoflurane and sevoflurane were greater than halothane. Isoflurane and sevoflurane showed changes of EEG as high voltage slow waves, burst suppression, flat EEG and sporadic spikes with increasing concentrations, while halothane showed only high voltage slow waves even in high concentrations.
2.The suppression of reactive capability to electrical sciatic nerve stimulation was greater in halothane than isoflurane and sevoflurane in cats. Cardiovascular changes produced by anesthetic agents and electrical stimuli were roughly correlated with changes in neuronal firing in
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the central nervous system. We investigated differences between volatile anesthetics in their suppressive effects on cardiovascular changes induced by tracheal intubation and skin incision in patients undergoing elective surgery. A similar finding to the animal study was obtained.
3.We compared anticonvulsant effects of volatile anesthetics in lidocaine-induced seizure, penicillininduced status epilepticus, bicuculline-induced seizure and amygdaloid kindling-induced seizure in cats. Although the order of potencies in anticonvulsant effects of three agents were divergent between different seizure models, isoflurane showed greater potent anticonvulsant effects. This result indicates that anticonvulsant effects of volatile anesthetics involve actions on GABA_A-receptors, suppression of general neuronal firing and suppression of cortical spreading process of epileptoid volleys.
4.MK8O1 inhibited enflurane-induced seizure, but did not depress frequency of enflurane-induced sporadic spikes nor augmentation of somatosensory evoked response in cats. This result indicates that NMDA-receptor is involved in the propagation of epileptic volleys in the brain but not in the epileptogenesis of enflurane-induced seizure. Less
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