In vivo release of [3H]-purines by quinolinic acid and related compounds

Abstract
1 In vivo release of [3H]-purines from the cortex of anaesthetized rats was measured and the actions of excitatory amino acids and analogues investigated. 2 High KCl, N-methyl-dl-aspartate (NMDLA) and quinolinic acid produced a large increase in basal release of labelled materials. Glutamate, quisqualate and kainate had less effect. 3 The N-methyl-d-aspartic acid (NMDA)-preferring receptor antagonist, 2-amino-7-phosphono-heptanoic acid, significantly reduced the release evoked by NMDLA and quinolinate but not that produced by the other agonists. 4 Kynurenic acid, a compound metabolically related to quinolinic acid, reduced the release due to NMDLA and quinolinate but not glutamate. 5 The results add further support to the suggestion that quinolinic acid acts on the NMDA-preferring receptor.