Abstract
The effects of riboflavin deficiency on muscle protein, RNA and DNA, and on the incorporation of 14C-amino acid into muscle proteins have been studied on rats receiving 16% protein diet, or 16% protein diet followed by protein-free diet or 16% protein diet followed by protein-free diet and 40% protein diet. In each of the dietary conditions, protein content, RNA/DNA and protein/DNA ratios in muscle were found to be decreased in riboflavin deficiency. The incorporation of 14C-amino acid into muscle proteins decreased in riboflavin-deficient rats receiving either 16% protein or 16% protein diet followed by protein-free diet and 40% protein diet. But in riboflavin-deficient rats receiving protein-free diet following 16% protein diet, the incorporation of 14C-amino acid into muscle proteins was found to be enhanced. It has been suggested from these studies that decreased protein content in muscle of riboflavin-deficient rats in each of the dietary conditions is due to both reduced synthesis and increased catabolism of proteins, and the catabolism of muscle proteins in riboflavin-deficient rats is intensive when they receive protein-free diet.
