Analysis of extracellular gamma-aminobutyric acid, glutamate and aspartatein cat visual cortex by in vivo microdialysis and capillary electrophoresis-laser induced fluorescence detection

To investigate the influence of a partial sensory deprivation on the extrac ellular concentration of amino acid neurotransmitters in cat visual cortex, a capillary electrophoresis method was developed for the quantification of gamma -aminobutyric acid (GABA), glutamate (Glu) and aspartate (Asp) in in vivo microdialysis samples of cat brain. Microdialysis samples from differ ent regions of area 17 were obtained every 15-min using CMA 12 2-mm probes perfused with synthetic cerebrospinal fluid and derivatized using fluoresce in isothiocyanate (FITC). Laser-induced fluorescence (LIF) detection was em ployed. Good selectivity was obtained with a berate buffer (20 mM, pH 10.25 ). The whole procedure, including the washing step takes only 15 min. The c onditions fur derivatization and separation were optimized. The parameters for validation such as linearity, precision and detection limit are also re ported. The results are consistent with those of HPLC but, as the sample vo lumes needed are only 1-5 nl, a much better time resolution can be obtained . (C) 2001 Elsevier Science B.V. All rights reserved.