Uptake and metabolism of glutamine in cultured kidney cells.
The metabolism of glutamine was investigated in cultured rat kidney cells. Glutamine utilization and product formation were followed as a function of time at either 10 microM or 1 mM initial glutamine concentration. At 1 mM glutamine, glutamate and gamma-glutamylglutamate were the major products formed at the end of a 5-min incubation period; glutamate accounted for 46% while gamma-glutamylglutamate accounted for 33% of the glutamine utilized. With time, glutamate continued to accumulate while gamma-glutamyl peptide formation leveled off. The role of gamma-glutamyl transpeptidase was assessed by using hippurate, a physiological activator of gamma-glutamyl transpeptidase and acivicin, L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid, an inhibitor of gamma-glutamyl transpeptidase. Hippurate, 4 mM, increased the utilization of glutamine and the formation of glutamate, gamma-glutamyl peptides and ammonia. Exposure of cells to acivicin resulted in 98% inhibition of gamma-glutamyl transpeptidase without effecting phosphate-dependent glutaminase activity. Acivicin inhibition resulted in a decreased utilization of glutamine and product formation as compared to control; 5-oxoproline appearance fell 70%. The fractional distribution of glutamine carbon and nitrogen into its metabolic products in control, hippurate and acivicin-treated cells showed no change at the end of 60 min. The data provide evidence that gamma-glutamyl transpeptidase utilizes glutamine and forms gamma-glutamyl peptides in cultured kidney cells.
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D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D005973:Glutamine / Q000378:metabolism*; D006626:Hippurates / Q000494:pharmacology; D007555:Isoxazoles / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051381:Rats; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D006626:Hippurates; D007555:Isoxazoles; D005973:Glutamine; D005723:gamma-Glutamyltransferase; C006303:acivicin; C030514:hippuric acid