Amino acid induced orotic aciduria.

Twenty amino acids were examined for their effects on urinary orotic acid excretion. Except for arginine and ornithine, all of the remaining amino acids tested induced a mild orotic aciduria in rats 2 hours post feeding. Two ammonium salts, and urease also acted, as inducers of orotic aciduria. The ammoneogenic properties of the amino acids tested could not solely explain the induced excretion of orotic acid. Only serine, glutamine, NH4Cl, (NH4)2CO3, and urease increased orotic acid excretion in the 24 hour fasted rat. Administration of 0.5 mmoles of arginine or ornithine ameliorated the mild orotic aciduria induced by either glycine or lysine. Arginine was shown to be more efficacious in preventing glycine induced orotic aciduria than was ornithine. Amino acid induced orotic aciduria is dependent upon the physiological state of the animal, varying with the state of digestion and the supply of arginine.