Studies on Dietary Effects on Hepatic Histidase and Alanine Transaminase of Rats Fed on either Histidine Controlled or Imbalanced Diet

Liver glutamic pyruvic transaminase (GPT) activity of rats fed on a histidine imbalanced diet was higher than those of animals fed on a histidine controlled or corrected diet. Histidase activity was not changed by varying the amount of histidine in diets from zero to 0.8% when all other amino acids were presented in a balanced composition, and the excessive amount of histidine in a low protein diet increased the activity of histidase slightly. Histidase activity increased linearly with each increase of the amount of phenylalanine in the diets from zero to 0.4%, but the further increase of phenylalanine (2%) did not increase the enzyme activity any more. On the other hand, GPT decreased by increaseing the amount of both histidine and phenylalanine in the diet along with the increase of biological value of the diet. Replacing the carbohydrate with hydrogenated coconuts oil did not alter the activity of histidase, and increased the activity of GPT.