Identification of α-Ketoglutaramate in Rat Liver, Kidney, and Brain

The presence of α-ketoglutaramate was shown in rat liver, kidney, and brain by application of an isotope dilution procedure; concentrations of 7.6, 4.7, and 10.7 µmoles per kg were found, respectively. The finding of increased concentrations of α-ketoglutaramate in cerebrospinal fluid in patients with hepatic coma was verified. Studies on rat kidney preparations, together with other considerations, provide no evidence for a physical linkage between glutamine transaminases and ω-amidase. The data suggest that α-ketoglutaramate is a normal tissue constituent formed by transamination of glutamine. Its accumulation in the cerebrospinal fluid in hepatic coma seems to reflect increased utilization of ammonia for glutamine synthesis and increased transamination of glutamine, as well as the relatively low ω-amidase activity of brain.