GLUTAMINE KINETICS IN BURN PATIENTS COMPARISON WITH HORMONALLY INDUCED STRESS IN VOLUNTEERS

Objective: To assess the acute and protracted adaptive response of per ipheral glutamine kinetics to a severe injury. Design: Comparison stud y. Setting: Clinical research center at a university-affiliated hospit al. Patients: Six severely burned men and five young healthy men. Inte rventions: The catabolic hormones epinephrine, cortisol, and glucagon were infused simultaneously into the femoral artery of five healthy vo lunteers, thus acutely simulating the hormonal milieu associated with a severe injury. Main Outcome Measures: Whole-body glutamine flux and peripheral glutamine kinetics were determined using glutamine labeled with nitrogen 15 and net balance measurements in patients 2 weeks foll owing a severe burn injury. Identical measurements were made in the he althy volunteers before and following 4 hours of catabolic hormone inf usion. Results: Whole-body glutamine flux increased to a similar exten t in both the burn patients and in volunteers following catabolic horm one infusion. In comparison with their basal kinetics, the hormonally simulated acute stress in the volunteers induced a significant efflux of glutamine from the leg by greatly increasing the rate of glutamine appearance. In contrast, burn patients had a significant decrease in t heir rate of glutamine appearance and achieved a similar net loss of g lutamine from the leg only by a compensatory decrease in peripheral gl utamine consumption. Conclusions: These findings suggest that in the a cute stress response, skeletal muscle preferentially releases glutamin e from its free intracellular pool. as this reserve becomes depleted, net glutamine efflux is maintained by decreasing its rate of muscle gl utamine utilization. These results suggest a failure of muscle to augm ent de novo glutamine synthesis and support the conclusion that glutam ine is a conditionally essential amino acid during critical illness.