METABOLIC RESPONSE TO INJURY AND SEPSIS - CHANGES IN PROTEIN-METABOLISM

The metabolic response to trauma and sepsis involves an increased loss of body proteins. Specific sires of changes of protein and amino acid metabolism have been identified. In skeletal muscle, the rate of prot eolysis is accelerated greatly. The rate of protein synthesis also may be increased but not enough to match thr increase in degradation. Int ramuscular glutamine concentration is decreased because of increased e fflux and possibly decreased de novo synthesis. In the liver, the rate of synthesis of selected proteins (i.e., albumin,; transferrin. preal bumin, retinol-binding protein, and fibronectin ) is decreased, wherea s acute phase protein synthesis is accelerated. Tissues characterized by rapidly replicating cells, such as enterocytes, immune cells, granu lation tissue, and keratinocytes, exhibit early alterations in the cas e of decreased protein synthesis capacity. In these tissues, glutamine use is accelerated. Increased stress hormone (cortisol and glucagon) and cytokine secretion. as well as intracellular glutamine depletion, are potential mediators of altered protein metabolism in trauma and se psis. However, the relative importance of these factors has not been c larified. Therapy of acute protein catabolism may include the use of b iosynthetic human growth hormone. possibly in combination with insulin -like growth factor-1, and the administration of metabolites at pharma cologic doses. We recently studied the effects of carnitine and alanyl -glutamine administration in severely traumatized patients. We found t hat both carnitine and the glutamine dipeptide restrained whole-body n itrogen loss without affecting selected indices of protein metabolism in the skeletal muscle. (C) Elsevier Science Inc. 1997.