title: On-line derivatization for continuous and automatic monitoring of brain extracellular glutamate levels in anesthetized rats: a microdialysis study.
abstract: Glutamate is an important excitatory amino acid in central nervous system. We developed a method for in vivo, continuous and automatic monitoring of brain extracellular glutamate, as well as other amino acids in anesthetized rat. This method involves the use of microdialysis perfusion technique and a high-performance liquid chromatography system equipped with a fluorescence detector. The microdialysate (perfused at a flow-rate of 1 microl/min) was on-line derivatized with o-phthaldehyde (perfused at 2 microl/min) through a mixing tee prior to the injection onto the HPLC column. The efficiency of this on-line derivatization was equivalent to that performed with an off-line manner. The effect of cerebral ischemia (2 h) and reperfusion (2 h) in brain cortex of anesthetized rats was monitored using this method. In addition to glutamate, extracellular concentrations of other amino acids, such as aspartate, glutamine, glycine, taurine and gamma-aminobutyric acid, were also simultaneously monitored with this on-line method. Since monitoring of extracellular amino acids by microdialysis perfusion is intensively used in neuroscience investigations, this simple and convenient method would be useful in the future applications.
authors.affiliation: Department of Education and Research, Taichung Veterans General Hospital, Taiwan. csymdr@vghtc.vghtc.gov.tw
authors.forename: C S
authors.initials: CS
authors.lastname: Yang
authors.forename: P J
authors.initials: PJ
authors.lastname: Tsai
authors.forename: W Y
authors.initials: WY
authors.lastname: Chen
authors.forename: W J
authors.initials: WJ
authors.lastname: Tsai
authors.forename: J S
authors.initials: JS
authors.lastname: Kuo
mesh_terms: D000758:Anesthesia; D000818:Animals; D001224:Aspartic Acid / Q000032:analysis; D001322:Autoanalysis; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005110:Extracellular Space / Q000737:chemistry*; D018698:Glutamic Acid / Q000032:analysis* / Q000378:metabolism; D005973:Glutamine / Q000032:analysis; D005998:Glycine / Q000032:analysis; D008297:Male; D017551:Microdialysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013654:Taurine / Q000032:analysis; D020301:Vasospasm, Intracranial / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000032:analysis; D009764:o-Phthalaldehyde
chemical_list: D005973:Glutamine; D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D009764:o-Phthalaldehyde; D005998:Glycine