Amino acid supply and protein metabolism in isolated perfused rat skeletal muscle.

The uptake of amino acids by the perfused rat hind-limb at increasing perfusate amino acid concentrations was studied both in the presence and absence of insulin. The uptake of the essential amino acids could be correlated with their concentrations in muscle protein. A net protein synthetic rate was calculated from the predicted incorporation of phenylalanine and was 33 nmol h-1g-1, a value in good agreement with those obtained in other studies. The possible significance of the supply of leucine in the regulation of muscle protein synthesis is considered.