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Regulation of glutamate biosynthesis and release in vitro by low levels of ammonium ions


, : Regulation of glutamate biosynthesis and release in vitro by low levels of ammonium ions. Brain Research 237(2): 339-350

The content and release of endogenous amino acids from isolated rat hippocampal slices were measured. The tissue was perfused with control media and pulsed with high K media to induce synaptic release. Pathophysiological concentrations of NH4+ (3-5 mM) were added to the control medium for 60 min prior to the induced release. Amino acids belonging to the putative transmitter group were released extensively during K perfusion and, except for glutamate, even after NH4+ perfusion. The spontaneous secretion of glutamate increased slowly after the addition of NH3. The incorporation of 14C from radiolabeled glucose and acetate into the amino acid fraction was studied in the presence of NH3-containing media. Glucose was utilized to a moderately increasing extent, but acetate-derived radioactivity was strikingly decreased in the amino acid fraction during NH3 perfusion. The decreased acetate incorporation into amino acids was mainly due to an inhibition by NH3 of the accumulation of acetate by the CNS tissue.

Accession: 006288096

PMID: 6123369

DOI: 10.1016/0006-8993(82)90446-2

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