Presynaptic supperssion by an inhalation anesthetic
Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||Shiga University of Medical Science(1999)|
TAKENOSHITA Makoto Shiga University of Medical Science, Dept. of Anesthesiology, associateprofessor, 医学部, 助教授 (00144486)
NOSAKA Shuichi Shiga University of Medical Science, Dept. of Anesthesiology, professor, 医学部, 教授 (80237833)
ASAI Tatsuya Fukui University, Dept. of Human and Artificial Intelligent Systems, assistant professor, 工学部, 講師 (60291374)
UCHIDA Ichiro Osaka University Medical School, Dept. of Anesthesiology, assistant professor, 医学系研究科, 講師 (00232843)
吉矢 生人 大阪大学, 医学部附属病院, 教授 (80028505)
上山 博史 大阪大学, 医学部附属病院, 助手 (10243205)
春名 優樹 大阪大学, 医学部, 助手 (00291443)
|Project Period (FY)
1997 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥12,800,000 (Direct Cost : ¥12,800,000)
Fiscal Year 1999 : ¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1998 : ¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥8,500,000 (Direct Cost : ¥8,500,000)
|Keywords||halothane / inhalation anesthetic / mechanism of anesthesia / synaptic transmission / presynapse / slice / voltage-sensitive absorption dye / calyx of MNTB / シナプス伝達 / 吸入麻酔薬 / EPSP / シナプス電流 / ラット / スライス標本|
Introduction : The action of general anestheticson the presynapse is controversial, both no action and suppression are reported. This ambiguity is due to the difficulty of direct recording from the presynapse. In the present study, we used two methodsto observe the anesthetic' s presynaptic action directly. One is to use the voltage sensitive dye, and another is to patch-clamp the large presynaptic terminal of the calyx of MNTB (Medial Nucleus of the trapezoid body).
Method : (1) Slice preparations of 400μ from the spinal cord of the rat (Ca 2 weeks old) was stained with a voltage-sensitive absorption dye RH-482, and perfused with Ringer solution oxygenated with 95% 02 + 5% CO2.The dorsal root was stimulated and the light absorption changein the dorsal horn was measured.The presynaptic change was isolated by adding AP-5 and CNQX.(2) Slice preparations of 300μ from the pons of the rat (Ca 2 weeks old) was perfused with Ringer solution oxygenated with 95% 02 + 5% CO2.The presynaptic terminal of the calyx of MNTB was patch clamped and whole cell recordings were made Halothane was dissolved in the perfusing Ringer solution.
Result : (1) The presynaptic potential change was dose-dependently and reversibly suppressed by halothane. This suppression was also observed with the solution containing Ba, Cd, bicuculline, strychnine. (2) The EPSC was dose-dependently and reversibly suppressed by halothane.Halothane did not suppress the presynaptic Ca current, nor presynaptic Na current, nor presynaptic action potential. But halothane hyperpolarized the presynapse.
Conclusion : The present study showed that halothane suppress and hyperpolarize the presynapse. But the precise mechanism is still largely unknown.
Research Output (3results)