Increase in cytochrome contents of liver mitochondria on feeding rats a low casein diet.

Williams et al. (1) investigated the changes in amounts of total mitochondrial protein and cytochromes in the liver of rats fed a protein-free diet for a long period, and found that there was a marked similarity between changes in amount of total mitochondrial protein and that of cytochromes. Present experiments were performed to clarify whether under a more mild protein-deficient state the relationships found by Williams are applicable or not by investigating the changes in contents of cytochromes per unit amount of mitochondrial protein when rats were fed a low case diet. A 4% casein diet was used as a low casein diet, and a 25% casein diet was used as a control diet. Rats were fed the test diets for 70 to 90 days. The results show that the contents of all cytochromes a, b, and c1 + c assayed and expressed as nmoles per mg of mitochondrial protein were significantly higher in rats fed a low casein diet than those in rats fed a control diet. These suggest that relationships found by Williams in a severe protein-deficient state would not be applicable in a more mild protein-deficient state.