Factors affecting amino acid induced orotic aciduria in rats.

Administration of individual amino acids is known to induce an orotic aciduria. The present studies show that the induction of orotic aciduria by glycine is highly influenced by stage of digestion of the test animal and the nitrogen content of the test diet. Short term fasting for 24 hours prevented glycine induced orotic aciduria. However, longer term fasting for 1, 3, 5, or 7 days resulted in a return in the ability of glycine to stimulate pyrimidine biosynthesis. The maximum induced orotic aciduria occurred after 3 days of fasting. The ability of glycine to induce orotic aciduria in the fed rat was also dependent on the dietary protein content. Glycine injections were unable to elicit an orotic aciduria in rats fed a protein-free diet. Addition of increasing quantities of nitrogen to the basal diet resulted in a proportional increase in glycine induced orotic aciduria.