Skeletal Muscle Is Anabolically Unresponsive to an Amino Acid Infusion in Pediatric Burn Patients 6 Months Postinjury

Abstract

To evaluate leg muscle, whole-body muscle, and whole-body nonmuscle protein response to anabolic signaling of amino acids in pediatric burn patients at 6 months after injury. Burn injury is associated with a catabolic state persisting years after the injury. The tissue response to nutritional signaling (eg, amino acids) plays a critical role in tissue protein net balance via coordination of protein synthesis and breakdown mechanisms. A total of 10 patients (7.4 ± 3.8 years; 27.4 ± 14.7 kg) and 5 healthy young males (22 ± 3 years; 76 ± 15 kg) underwent an 8-hour stable isotope infusion study. During the last 3 hours, an amino acid solution (10% Travasol, Clintec Nutrition, Deerfield, IL) was infused. Femoral arterial and venous blood samples and muscle biopsy samples were collected throughout the study. A P value of less than 0.05 was considered statistically different. During amino acid infusion, leg muscle protein synthesis rate significantly increased (P < 0.05) in both groups, however, in the burn group, protein breakdown also increased, although nonsignificantly. As a result, protein net balance remained negative. In the control group, breakdown nonsignificantly decreased resulting in a significant increase (P < 0.05) in muscle protein net balance. Whole-body protein breakdown was significantly higher in the burn patients. In pediatric burn patients at 6 months postinjury, leg muscle protein net deposition is unresponsive to amino acid infusion; and whole-body protein breakdown is significantly higher than in the control group.