title: Measurement of GABA and glutamate in vivo levels with high sensitivity and frequency.
abstract: In the present protocol, we demonstrate a high-performance liquid chromatography (HPLC) system that enables detection of very low amounts of gamma-aminobutyric acid (GABA) (0.03 pmol) and glutamate (0.8 pmol). The HPLC system consists of two pumps, an electrochemical detector, a high-pressure six-way switching valve, a guard column, a microbore column, and a column oven. A microdialysis probe was implanted in the right parietal cortex in rats. Dialysates were collected every 5 min and were split into two equal aliquots for separate analysis of GABA and glutamate. After derivatization with o-phthalaldehyde (OPA), samples were isocratically separated and purified by the guard column. To make the peak of GABA or glutamate appear in an opportune place in a chromatogram, a six-way switching valve was used to control the eluate containing GABA or glutamate to be led to the microbore column and electrochemical detector. By the use of this system, decrease in extracellular concentration of GABA, which precedes the appearance of electrical discharge initiated by hyperbaric oxygen (HBO2) exposure, was detected by microdialysis at the time resolution of 5 min.
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama City, Okayama 700-8558, Japan.
authors.forename: Shan
authors.initials: S
authors.lastname: Zhang
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takeda
authors.forename: Shingo
authors.initials: S
authors.lastname: Hagioka
authors.forename: Ken
authors.initials: K
authors.lastname: Takata
authors.forename: Hisami
authors.initials: H
authors.lastname: Aoe
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakatsuka
authors.forename: Masataka
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Morita
mesh_terms: D000818:Animals; D016477:Artifacts; D001923:Brain Chemistry / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes / Q000592:standards; D045604:Extracellular Fluid / Q000737:chemistry / Q000378:metabolism; D018698:Glutamic Acid / Q000032:analysis* / Q000378:metabolism; D006931:Hyperbaric Oxygenation; D008297:Male; D017551:Microdialysis / Q000295:instrumentation / Q000379:methods*; D009448:Neurochemistry / Q000295:instrumentation / Q000379:methods*; D010100:Oxygen / Q000494:pharmacology; D010296:Parietal Lobe / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D005680:gamma-Aminobutyric Acid / Q000032:analysis* / Q000378:metabolism
chemical_list: D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D010100:Oxygen