Beschreibung:
<jats:p>Previous reports have shown that nitrogen (N) supply as nonessential amino acids (NEAAs) is required for normal growth in rats and that glutamate (Glu) is one of the most potent growth promoters among NEAAs. Our recent N‐balance study has also indicated that dietary Glu‐N was retained more than glycine‐N or glutamine‐N, suggesting differences in N‐metabolisms of these NEAAs. Thus, the present study aimed to compare N‐metabolism of dietary Glu with those of the other NEAAs using stable isotope techniques.</jats:p><jats:p>Fischer strain male rats were given hourly meals containing [<jats:sup>15</jats:sup>N]Glu or other [<jats:sup>15</jats:sup>N]NEAAs. Concentrations and <jats:sup>15</jats:sup>N‐enrichments of each amino acid (AA) in portal and arterial plasma were measured to estimate their first‐pass N‐metabolism and their N‐contribution for systemic AA.</jats:p><jats:p>Virtually all of the dietary Glu‐N and aspartate‐N were metabolized in the gut for production of various AA such as alanine and citrulline. Meanwhile, substantial amount of the other dietary NEAAs were released into the portal vein directly without any metabolism in the gut. The incorporations of dietary Glu‐N in circulating AA were similar to those of aspartate‐N, alanine‐N and amino‐N of glutamine but greater than those of amide‐N of glutamine, glycine‐N, serine‐N. These results suggest efficient utilization of dietary Glu‐N for the intestinal synthesis of the other NEAAs and hence its significance as N‐source for whole body.</jats:p><jats:p><jats:bold><jats:italic>Grant Funding Source</jats:italic></jats:bold><jats:italic>: Ajinomoto Co., Inc.</jats:italic></jats:p>