The contents of alanine, proline, glycine, GABA, glutamate, and aspartate were measured in four bundles of axons (designated areas A through D) from the circumesophageal connective of the lobster (Homarus americanus). The contents of these amino acids were also determined in individual axons within specific bundles and in the external sheath covering the circumesophageal connective. Within the nerve bundles the levels of aspartate were highest of the amino acids measured, ranging from 1.95 ± 0.12 μmol/mg protein in area C to 7.55 ± 0.54 μmol/mg protein in area B. On the other hand, GABA had the lowest value in the four bundles; its highest level was found in area C (0.083 ± 0.006 μmol/mg protein) and the lowest in area B (non detected). The content of glycine ranged from 1.63 ± 0.14 (area C) to 2.52 ± 0.32 μmol/mg protein in area A; that for glutamate ranged from 0.390 ± 0.019 (area C) to 1.01 ± 0.013 (area B). The contents of alanine and proline changed relatively little from bundle to bundle. The content of aspartate was the highest of any of the amino acids assayed in individual axons (with diameter in the range of 40 to 65 μ) dissected from areas B and C. Glycine had the next highest content followed in order by glutamate, proline, and alanine. GABA was not detected in these axons. With the exception of GABA (which could not be detected), aspartate had the lowest level (0.066 ± 0.017) and glycine had the highest level (2.00 ± 0.498 μmol/mg protein) in the external sheath covering the the circumesophageal connective.
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience