Antagonist profile of 6,7-dichloro-3-hydroxy-2-quinoxalinecarboxylate at excitatory amino acid receptors in the neonatal rat spinal cord.

In the neonatal rat spinal cord, 6,7-dichloro-3-hydroxy-2- quinoxalinecarboxylate antagonised responses mediated at both N-methyl-D-aspartate (NMDA) and non-NMDA receptors. The antagonism of responses to NMDA was unsurmountable and mediated via an antagonist action at the allosterically-linked strychnine-insensitive glycine site. At non-NMDA receptors, 6,7-dichloro-3-hydroxy-2-quinoxalinecarboxylate appeared to act as a competitive antagonist at low concentrations and a non-competitive antagonist at higher concentrations. In contrast to published data, this antagonist did not distinguish between the responses mediated by DL-alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) and kainate.