The effect of Neurotransmitter on the anesthetic requiremeuts (MAC)

1996 Fiscal Year Final Research Report Summary

• Project/Area Number: 06454451
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Anesthesiology/Resuscitation studies
• Research Institution: The Jikei University School of Medicine
• Principal Investigator: TANIFUJI Yasumasa The Jikei University School of Medicine, Anesthesiology, Professor, 医学部, 教授 (00056847)
• Co-Investigator(Kenkyū-buntansha): ONOZAWA Hirosyi The Jikei University School of Medicine, Anesthesiology, Instructor, 医学部, 助手 (20277015) ; TORIUMI Kazuhiro The Jikei University School of Medicine, Anesthesiology, Instructor, 医学部, 助手 (50237161) ; TANAKA Tadashi The Jikei University School of Medicine, Anesthesiology, Instructor, 医学部, 助手 (30221394)
• Project Period (FY): 1994 – 1996
• Keywords: Neurotransmitter on the anesthetic requirements / MAC / 神経伝達物質 / マイクロダイアリシス / MAC / ノルアドレナリン / 海馬

Research Abstract

The mechanisms are not known by volatile anesthetic agento act on the nervous system to produce anesthesia. It has been reported that monoamine content such as DA,NA,5-HE in the brain region affects the anesthetic requirement, so it has been suggested that volatile anesthetics act on some aspect of synaptic transmission. The possibility was presumed that volatile anesthetics changed transmitter release to synaptic clefts. Recently the striatal dopamine levels in vivo have been investigated by a cerebral microdialysis technique under halothane or isoflurane administration, and it was reported that isoflurane or halothane increased the rat striatal dopamine levels. We got results that the effect of the halothane dose on the levels of dopamine in the rat striatum was investigated by the in vivo microdialysis technique, and the dopamine levels were found to increase deep halothane dose.
It is very difficult to distinguish cause from effect of the anesthesia when an increase in dopamine foll owed a higher dose of halothane. If dopamine content relates to the anesthetic requirement, the relation of dopamine to anesthesia state would be discussed.
Therefore, to determine whether an increase in dopamine in the striatum is related to the anesthesia state, we measured the changes in the anesthetic requirement caused by the administration of various concentrations of dopamine into the rat striatum by the microdialysis technique.
A ringer's solution containing two different concentrations of dopamine was continuously injected into the rat striatum directly through a microdialysis probe by a micro infusion pump during the measurement of MAC.We compared the MAC before and after administration of the dopamine and discussed the relationship between the dopamine content and the anesthesia state. The results of MAC changed by the administration of dopamine.
When 0.1 M/l of dopamine solution was administered through the microdialysis probe, MAC was not changed, however, when 1.0 M/l of the dopamine solution was administered through the microdialysis probe, MAC was decreased by about 30%. An increase in dopamine content in the rat striatum which was more than about 23pmol alters the anesthetic requirement, but less than about 5 pmol did not affect the anesthetic requirement.