Abstract
We have reported in the previous paper the metabolic changes in rats fed an amino acid diet depleted by one of the following essential amino acid, threonine, tryptophan, or phenylalanine. Similar experiments with rats force-fed a complete amino acid diet, lysine-free or methionine-free amino acid diet were conducted to observe changes in the urinary nitrogen and N'-methyl-nicotinamide (MNA), the liver tryptophan pyrrolase (TPase), tyrosine-α-ketoglutarate transaminase (TKase) activities, and the liver fat of the experimental rats 3 hours after the feeding on 5th day.
The results were similar with those obtained in the previous report that the urinary nitrogen and MNA, and the liver TPase and TKase activities of rats force-fed the lysine-free or methionine-free diet were higher than those of rats fed the complete amino acid diet.
However, it was indicated that differences between the values in all items of the lysine-free diet group and those of the complete amino acid diet group were lesser than differences in the previous experiments between the threonine-, tryptophan- or phenylalanine-free diet group and its control group fed the complete amino acid diet. This may be due to the specificity of the lysine metabolism. On the other hand, it was shown that the metabolic changes of rats fed the methionine-free diet were also specific and the changes were greater than those in the other groups.
