Changes of protein metabolism in liver and skeletal muscle following trauma complicated by sepsis.

The effects of trauma (laparotomy) and trauma complicated by sepsis (laparotomy and ligation and puncture of the cecum) on protein metabolism in liver and skeletal muscle were studied in rats. Unoperated animals served as controls. Rate of amino acid incorporation into proteins was determined in incubated liver slices and bundles of muscle fibers. Proteolysis in skeletal muscle was measured as release of tyrosine from incubated muscle biopsies. Protein synthesis in liver tissue was increased by 42% following trauma and by 164% following trauma and sepsis. In skeletal muscle amino acid incorporation into proteins was reduced by 50% in both conditions while protein degradation was enhanced by about 70%. Thus when injury was complicated by sepsis the metabolic response was augmented in liver but not in skeletal muscle. One reason for this difference might be that changes of protein metabolism in trauma and sepsis are regulated by different mechanisms in liver and skeletal muscle. The results also indicate that increased amino acid supply from peripheral protein breakdown is not the only signal for enhanced hepatic protein synthesis in trauma and sepsis.