Hyperammonemic alterations in the metabolism of glutamate and aspartate in rat cerebellar astrocytes.
Pathophysiological concentrations of ammonia, both in vivo and in vitro, suppressed the production of 14CO2 from 14C-labelled glutamate and aspartate in astrocytes isolated from the rat cerebellum. Suppression of 14CO2 production with (aminooxy)acetic acid but not with glutamic acid diethyl ester indicated that transamination plays a major role in the oxidation of glutamate carbons. Activities of the enzymes, aspartate amino-transferase, alanine aminotransferase and glutaminase were decreased while those of glutamate dehydrogenase and glutamine synthetase were enhanced in the cerebellar astrocytes during hyperammonemic states. These results suggest an impairment of astrocytic glutamate metabolism during hyperammonemia.
School of Life Sciences, University of Hyderabad, India.
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VL
Rao
C R
CR
Murthy
D000085:Acetates / Q000494:pharmacology*; D000410:Alanine Transaminase / Q000378:metabolism; D000625:Aminooxyacetic Acid / Q000494:pharmacology; D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism*; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism*; D018691:Excitatory Amino Acid Antagonists; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism* / Q000494:pharmacology; D005972:Glutaminase / Q000378:metabolism; D066298:In Vitro Techniques; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values
D000085:Acetates; D002250:Carbon Radioisotopes; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D000625:Aminooxyacetic Acid; C011829:glutamic acid diethyl ester; D001224:Aspartic Acid; D005969:Glutamate Dehydrogenase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D005972:Glutaminase; D005974:Glutamate-Ammonia Ligase; C018824:ammonium acetate