The Crayfish Fast Extensor Muscle Exhibits Both NMDA And Non-NMDA Receptor Activity

Abstract

In the neuromuscular junction of the crayfish, the excitatory neurotransmitter is glutamate. There are two types of glutamate receptors, N-methyl-D-aspartate (NMDA) and non-NMDA receptors, both of which have been demonstrated to be present in the opener muscle and deep abdominal extensor muscle. The crayfish fast extensor muscle, however, is an understudied preparation whose receptor types are undocumented. Using antagonists for both NMDA and non-NMDA receptors (2-amino-5-phosphonovaleric acid, or APV, and 6-cyano-7-nitroquinoxaline-2,3-dione, or CNQX, respectively, at a concentration of 10-5 M) to inhibit the generation of excitatory junction potentials (EJPs), this study demonstrates the existence of both NMDA and non-NMDA receptors in the fast extensor muscle. Further, results indicate that antagonist binding in this preparation is easily reversible, and that the two glutamate receptor types have different receptor-ligand interactions as evidenced by differences in kinetics.