Effects of partial hepatectomy on the enzymes of cerebral glutamate and branched-chain amino acid metabolism.
Cerebral activities of glutamate dehydrogenase (GDH), glutamine synthetase (GS), and branched-chain amino acid aminotransferase (BCAA-T) along with the levels of ammonia in serum and brain were determined in normal, sham-operated and partially hepatectomized rats. Mild hyperammonemia was observed in sham-operated animals, and the cerebral activities of all the enzymes studied were found to be decreased when compared with those of normal animals. In hepatectomized animals, blood and brain ammonia levels were elevated further. In these animals, GS activity returned to the normal values and that of BCCA-T was elevated, while there was a continued suppression of GDH activity. These results were discussed in relation to the utilization of BCAA (leucine, isoleucine, and valine) for the synthesis of glutamate and glutamine in brain in hyperammonemic states.
Jessy
J
J
Department of Physiology & Biophysics, University of Health Sciences, Chicago Medical School Il 60064.
Rao
V L
VL
Murthy
C R
CR
D000597:Amino Acids, Branched-Chain / Q000378:metabolism; D000641:Ammonia / Q000032:analysis / Q000097:blood; D000818:Animals; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D006498:Hepatectomy; D051381:Rats; D011919:Rats, Inbred Strains; D000637:Transaminases / Q000378:metabolism*
D000597:Amino Acids, Branched-Chain; D000641:Ammonia; D005969:Glutamate Dehydrogenase; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase; D005974:Glutamate-Ammonia Ligase