DEPRESSION OF ALANINE TRANSAMINASE ACTIVITY IN THE LIVER OF RATS BEARING WALKER CARCINOMA 256.

Summary Alanine transaminase activity in the liver of adult rats (350–450 gm.) fell progressively from the 10th through the 30th day of growth of Walker carcinoma 256. The enzyme activity decreased to a level about 30 per cent of that found in comparable rats of the same age without tumors. Loss of enzyme activity occurred concurrently, with a gradual loss of carcass weight. Treatment with cortisol (4 mg/kg, administered during the first 10 days of tumor growth) increased the activity of alanine transaminase in liver 2.5-fold, but the same dose did not alter transaminase activity when the tumors were large (days 20 through 30). The activity of this transaminase could be raised to normal in the presence of large tumors by feeding a diet containing 75 per cent casein. When this high-protein diet was fed, treatment with cortisol (4 mg/kg) increased alanine transaminase activity fourfold. Tyrosine transaminase and tryptophan pyrrolase differed from alanine transaminase in that both of these enzymes were increased four- to fivefold by cortisol (10 mg/kg) in the livers of rats with established Walker tumors.