Postsurgical Muscle Protein Turnover in Perfused Hindquarters of the Rat

ABSTRACT. Skeletal muscle protein synthesis and degrada-tion were measured simultaneously in perfused hindquarters of adult female rats 0, 2, and 4 days after surgical trauma. In order to explore the role of decreased postoperative nutrient intake on muscle protein turnover, a group of rats were pair-fed to the level of food consumed by surgical traumatized animals. Protein synthesis was measured by the incorporation of 3H-L-phenyl-alanine into the myofibrillar (contractile) and sarcoplasmic (soluble) proteins of gastrocnemius muscle. Protein degradation rates were calculated from the release of myofibrillar 3-methyl histidine (3MH) during the perfusion. Surgical trauma signifi-cantly depressed myofibrillar and sarcoplasmic protein syn-thetic rates by 33 and 29%, respectively. Protein degradation, as assessed by 3MH release into perfusate, increased 25 % on the second postoperative day but returned to control levels b