Selective potentiating effect of beta-p-chlorophenylglutamate on responses induced by certain sulphur-containing excitatory amino acids and quisqualate

In dorsal horn neurones of the cat spinal cord iontophoretically administered (+/-)-beta-p-chlorophenylglutamate (chlorpheg) markedly enhanced the excitatory responses induced by L-homocysteate, L-homocysteine sulphinate, S-sulpho L-cysteine, L-cysteate and quisqualate, while responses to NMDA, kainate, L-glutamate, L-aspartate and L-cysteine sulphinate were generally unaffected. Preliminary data obtained on frog spinal cord in vitro supports the possibility that such selective potentiation may be due to differential inhibition by chlorpheg of amino acid uptake. No potentiating effects of chlorpheg were observed on spinal synaptic excitation.