Studies on glutamic-oxalacetic transaminase in the chicken

II. Effect of dietary protein on the activity of GOT in various chicken organs

Abstract

Day-old broilers (W. C.× W. P. R.) were fed a semipurified diet (C. P. 20%) which contained whole egg powder as a sole source of protein. At 3 weeks of age chicks were separated into 2 groups matched as to body weight. One group was continued to be fed control diet (C. P. 20%), while the other was received a high protein diet (C. P. 40%) for 15 days.
Chicks were sacrificed every other day and fresh samples of 2g of various organs were homogenized in a Potter-Elvehjem type homogenizer with 18ml of ice cold 0.1M phosphate buffer, pH7.6. Using this homogenate as a crude enzyme solution, GOT activity was determined by the method of Reitman-Frankel.
High protein diet caused an immediate increase in the activity of liver GOT and the maximal activity was obtained after 8 days which was 170% higher than the corresponding control chicks. In contrast, the changes in the activity of GOT in heart muscle, glandular stomach and pancreas of chicks fed high protein diet for 15 days were almost the same as those of control group, however, the activity of GOT in kidney of chicks fed high protein diet slightly increased after 15 days.
Liver homogenate was fractionated by the method of Hogeboom and the activities of GOT in the soluble and mitochondrial fractions were determined. High protein diet caused an immediate increase in the soluble fraction, but in the mitochondrial fractions no significantt elevation were observed.