Excitatory amino acids: 6-phosphonomethyltetrahydro-4-pyrimidinecarboxylic acids and their acyclic analogues are competitive N-methyl-D-aspartic acid receptor antagonists.

Abstract 6-Phosphonoalkyltetrahydro-4-pyrimidinecarboxylic acids and their acyclic equivalents were determined to be competitive N-methyl-D-aspartic acid (NMDA) receptor antagonists using a [ 3 H]-CPP binding assay. Results suggest that internal hydrogen bonding interactions may exert either a positive or negative influence on NMDA receptor affinity depending on whether an appropriate receptor active configuration is stabilized.