Failure of kynurenic acid to inhibit amino acid release from the ischemic rat cerebral cortex

The ability of a broad spectrum glutamatergic receptor antagonist, kynureni c acid (1 and 5 mM) to attenuate release of excitant and other amino acids from the ischemic cerebral cortex was examined in a four vessel occlusion r at model. Kynurenic acid, administered topically onto the cortex in artific ial cerebrospinal fluid using bilateral cortical cups, failed to attenuate ischemia-evoked release of aspartate, glutamate, phosphoethanolamine, tauri ne and at 1 (but not 5) mM it depressed GABA release. There was no effect o n basal, pre-ischemic, release. This result suggests that ischemia-evoked a mino acid release is not a significant consequence of the activation of ion otropic receptors by synaptically released glutamate. (C) 1999 Elsevier Sci ence Ireland Ltd. All rights reserved.