[Influence of prolonged protein-free diet on the amino acid content of blood and muscles in rats].

The influence of a protein-free diet in adult male rats has been evaluated for a 6-week period. Nitrogen retention, hepatic protein and free amino acid content in blood and muscle were determined as adaptation criteria. Long-lasting protein depletion did not modify the pattern of response affering in a shorter period: i.e. sparing of nitrogen and use of endogenous amino acids for protein synthesis. Except for lysine, arginine and histidine, the essential amino acids decreased in blood and the non-essential acids increased. The final effect was a decrease of the essential to non-essential amino acid ratio and a decrease in all amino acids in muscle.