Effects of glutamate and glutamic acid diethyl ester on the lobster muscle fibre and the frog spinal cord.

The effect of bath applications of glutamic acid diethyl ester (GDE) and glutamate on the lobster muscle fibre and the from spinal cord were examined. In the lobster muscle fibre GDE (2 X 10(-3) M) did not antagonize the depolarizing action of glutamate (10(-4) M). In the frog spinal cord a small reduction in the excitatory effects of glutamate (10(-4)-10(-3) M) after GDE pretreatment was found only if the latter was given in very high doses (over 2 X 10(-3) M) which stimulated the neuronal firing. These observations show that GDE is not a specific antagonist of glutamate in these tissues.