RELEASE OF ENDOGENOUS GLUTAMATE AND GAMMA-AMINOBUTYRIC-ACID FROM RAT STRIATAL TISSUE-SLICES MEASURED BY AN IMPROVED METHOD OF HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

The release of endogenous glutamate and gamma-aminobutyric acid (GABA) from rat brain tissue slices was studied using a tissue slice assay i n which detectable amounts of the amino acids were released from 1-2 m g of tissue. An improved method of high performance liquid chromatogra phy (HPLC) with electrochemical detection was employed to measure both glutamate and GABA after derivatization with o-phthalaldehyde and sul fide in a single isocratic HPLC analysis. The non-endogenous amino aci d? homoglutamine, was used as an internal standard in verifying the co nsistent derivatization of amino acids and in quantifying amounts of g lutamate and GABA released from the caudate-putamen tissue. The deriva tized amino acids (1-30 pmol) were detected as chromatographic peaks e luting at baseline level and foe of significant interfering co-eluates in a 25-30 min analysis time. (C) 1997 Elsevier Science B.V.