Supplemental effect of lysine on growth depression of rats fed wheat gluten diets containing excessive amount of some individual amino acids.

Abstract

The effects of lysine supplementation on the growth depression causes by the excessive addition of some individual amino acids to a wheat gluten diet in which lysine is the first-limiting amino acid were studied. Male weanling rats were fed 11.6% wheat gluten (equivalent to the N content of 10% casein) diets containing 5.0% of single amino acids, L-arginine-HCI, L-tryptophan, L-phenylalanine, L-methionine and L-tyrosine, with or without 0.6% of L-lysine ⋅HCl for 3 weeks. The growth retardation produced by the excess arginine was reversed by the sup-plement of lysine, but the adverse effects caused by the excessive addition of the other amino acids were not alleviated. The moderate elevations of arginine and lysine levels in blood plasma produced by excess arginine diet did not altered by the supplemental lysine. In contrast, the plasma levels of phenylalanine, tyrosine, tryptophan and methionine elevated by the excessive feeding of corresponding amino acid were decreased fairly by the supplement of lysine. The activities of liver arginase did not changed appreciably by the addition of excess arginine and the supplemental lysine. It is suggested that the decrease in growth when excess arginine is added to lysine-deficient diet causes the reduction of lysine utilization and increases need for lysine.