The aim of this study was to determine the time course of changes in extracellular fluid （ECF） concentrations of purines

amino acids

monoamines

and their metabolites in the striatum of rats during ischemia and reperfusion

using intracerebral microdialysis as the sampling technique. In rats subjected to 20 min forebrain ischemia by four-vessel occlusion

the concentrations of adenosine （Ade）

inosine （Ino） and hypoxanthine （Hyp） were found to rise markedly. These changes were accompanied by dramatically elevated levels of aspartate （Asp）

glutamate （Glu）

taurine （Tau）

γ-aminobutyric acid （GABA）

dopamine （DA） and norepinephrine （NE）

all of which gradually returned to baseline following reperfusion. Concomitantly

the levels of metabolite 3

4-dihydroxyphenylacetic acid （DOPAC） . homovanillic acid （HVA）

5-hydroxyindole-3-acetic acid （5-HIAA） and xanthine （Xan） decreased during ischemia and gradually recovered 60～ 90 min after reperfusion. It was concluded that during global brain ischemia

the ECF is flooded with both potentially harmful （e. g. Asp

Glu

DA） and protective （e. g. Tau

GABA

Ade） agents.