On the interaction of 2-amino-7-phosphono-heptanoic acid and quinolinic acid in mice.

It is shown that (a) peripheral injections of quinolinic acid cause neuronal excitation with a latency much less than that of convulsions due to quinolinic acid and (b) peripherally injected 2-amino-7-phosphono-heptanoic acid (2APH) does antagonise neuronal excitation due to quinolinic acid applied locally by microiontophoresis. It is concluded that the previously reported failure of 2APH to prevent quinolinic acid seizures is a reflection of different modes of action of quinolinic acid in causing neuronal excitation and convulsions, and does not contradict the suggestion that quinolinic acid acts at N-methyl-D-aspartate (NMDA) receptors in the brain.