Catabolic Hormones Alone Fail to Reproduce the Stress-Induced Efflux of Amino Acids

Abstract

To determine the impact of catabolic hormones on the pattern of amino acid efflux from human skeletal muscle during stress. Cohort analytical study. Burn intensive care unit and clinical research facility at a university hospital. Five patients with severe burns and five healthy volunteers of similar size and age. The net balance of amino acids across the leg was determined in five healthy volunteers prior to and following a 2-hour infusion of the catabolic hormones epinephrine, cortisol, and glucagon into the femoral artery. These results were compared with amino acid net balance measurements in five severely burned patients. Hormonal simulation of stress in the normal volunteers increased glutamine efflux from the leg to an extent similar to that of the burn patients. Alanine efflux, however, was not affected by the hormonal infusion. Because alanine efflux constituted a major proportion of the total peripheral amino acid catabolism in the burn patients, there was significantly less total amino acid nitrogen loss from the healthy volunteers receiving the stress hormones. Catabolic hormones alone fail to reproduce the stress-induced pattern and quantity of amino acid efflux from human skeletal muscle. This discrepancy is largely due to an unresponsiveness of alanine to hormonally induced muscle protein catabolism.