Further Observations on the Interaction Between Gluta Mate and Aspartate on Lobster Muscle

Abstract

1 The ability of bath-applied L-glutamate to enhance subsequent depolarizations produced by bathapplied L-aspartate on lobster muscle was further investigated by means 6 In a Na+-free (Li') medium, both the glutamate depolarization and the conditioning effect towards aspartate were largely abolished. With kainate however, Na+ was not apparently important either for evoking the kainate response or for producing the conditioning effect. 7 Bath-applied glutamate greatly enhanced and prolonged the time course of the iontophoretic aspartate potential with only a small effect on the glutamate potential; however, these effects were not maintained after washout of glutamate. In contrast, bath-application of aspartate depressed the aspartate potential while enhancing the glutamate potential. Some sites that were insensitive to iontophoretically-applied aspartate became clearly responsive to this agent during a bath-application of glutamate.8 It is proposed that during conditioning with bath-applied glutamate, kainate or domoate, some agonist is trapped by extrajunctional sites and is subsequently displaced by bath-applied aspartate to produce the long-term enhancement effect.

Cross‐Species Comparison of Metabolite Profiles in Chemosensory Epithelia: An Indication of Metabolite Roles in Chemosensory Cells

“…7B,D). Aspartate may also be enhancing glutamatergic neurotransmission (Shank and Freeman, 1975; Constanti and Nistri, 1978, 1979). In the lobster neuromuscular junction, aspartate and glutamate cooperatively increase activation of glutamate receptors.…”