The relation between plasma concentrations of glutamine and glycine and utilization of their nitrogens as sources of urinary ammonia.

Abstract

15N-Glycine, 15N-amino-labeled glutamine and 15N-amide-labeled glutamine were each infused in tracer amounts into 1 renal artery of acidotic dogs, to assess the proportion of the urinary NH3 derived from each precursor. When the plasma glycine concentration was increased by the intravenous infusion of unlabeled glycine, glycine N was utilized in increased amount as a source of urinary NH3. Similarly, when the plasma glutamine concentration was increased by the infusion of unlabeled glutamine, the amide and amino nitrogens of glutamine were both utilized in increased amounts as sources of urinary NH3. Elevation of the plasma glycine or alanine concentration did not reduce the utilization of the amide or amino nitrogens of glutamine as sources of urinary NH3. Small increases in the utilization of the glutamine nitrogens were observed, probably because attendant small increases in plasma glutamine concentration occurred.