The synergistic action of L‐glutamate and L‐aspartate at crustacean excitatory neuromuscular junctions.

Abstract

L-glutamate and L-aspartate simultaneously applied to the excitatory neuromuscular junctions of Maia squinado produce an increase in the conductance of the post-synaptic membrane much larger than the sum of conductance effects produced by the individual amino acids. An examination of the synaptic noise occurring during this synergistic action reveals that the elementary conductance events produced by aspartate are suppressed and that normal elementary conductance events produced by glutamate occur at an enormously increased rate. Aspartate caused this potentiation by inhibiting a system for transmitter inactivation in the region of the post-synaptic receptors, and this system under normal conditions prevents the access of externally applied glutamate to the synaptic receptors.