CATABOLIC HORMONES ALONE FAIL TO REPRODUCE THE STRESS-INDUCED EFFLUX OF AMINO-ACIDS

Objective: To determine the impact of catabolic hormones on the patter n of amino acid efflux from human skeletal muscle during stress. Desig n: Cohort analytical study. Setting: Burn intensive care unit and clin ical research facility at a university hospital. Patients: Five patien ts with severe burns and five healthy volunteers of similar size and a ge. Interventions and Measurements: The net balance of amino acids acr oss the leg was determined in five healthy volunteers prior to and fol lowing a 2-hour infusion of the catabolic hormones epinephrine, cortis ol, and glucagon into the femoral artery. These results were compared with amino acid net balance measurements in five severely burned patie nts. Results: Hormonal simulation of stress in the normal volunteers i ncreased glutamine efflux from the leg to an extent similar to that of the burn patients. Alanine efflux, however, was not affected by the h ormonal infusion. Because alanine efflux constituted a major proportio n of the total peripheral amino acid catabolism in the burn patients, there was significantly less total amino acid nitrogen loss from the h ealthy volunteers receiving the stress hormones. Conclusions: Cataboli c hormones alone fail to reproduce the stress-induced pattern and quan tity of amino acid efflux from human skeletal muscle. This discrepancy is largely due to an unresponsiveness of alanine to hormonally induce d muscle protein catabolism.