Glutamate and aspartate as mediators of neuromuscular excitation in the lobster

R. P. Shank, A. R. Freeman, W. J. McBride, M. H. Aprison

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16 Scopus citations


Aspartate is highly concentrated in excitatory axons within the walking limbs of the lobster, and is approximately three times higher in concentration than glutamate. In muscle and hemolymph, aspartate is present in much smaller amounts, and is less concentrated than glutamate. When applied to the external surface of lobster muscle fibers, aspartate alone is about one tenth as potent an excitatory agent, as is glutamate. However, when glutamate and aspartate are combined in concentrations proportional to their tissue contents (i.e. aspartate glutamate ratios of 2:1 to 4:1) the mixture is nearly as effective as an amount of glutamate equal to their sum. Hence, aspartate greatly reduces the concentration of glutamate required to evoke a marked excitatory response. These results are consistent with the view that neuromuscular excitation in the lobster is mediated by a combination of glutamate and aspartate, acting in concert.

Original languageEnglish (US)
Pages (from-to)127-131
Number of pages5
JournalComparative Biochemistry and Physiology
Issue number1 C
StatePublished - Jan 1 1975

ASJC Scopus subject areas

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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