The interrelationships between the quality of dietary protein and the maintenance of liver enzyme activity of rat's have been investigated. The results are as follows: With use of Amino acid composition of the dietary food protein as a criterion, it has been demonstrated that the rat's liver xanthine oxidase activity almost correspond with the protein score of experimental diets. Judging from these results and previously reported results the authors presume that under the fixed condition the activity response of rat's liver xanthine oxidase reflects the nutritive value of dietary food proteins.
Influences of protein quality and quantity upon metabolism and psychological behaviour of white rats exposed to vibration were observed for 13 weeks. 1. The unfavorable effects of the vibration upon the growth of animals were protected by the intake of much protein of good quality. 2. The hypertrophy of suprarenal gland caused from the vibration was found much heavier among the rats fed on the diet of poor protein than the rats fed on the rich protein. 3. The activities of xanthin oxidase of livers were apparently different by the quality and quantity of protein fed on. 4. The psychological behavior was also influenced by the kinds of diet.