Increased peripheral amino acid release following burn injury

Turnover rates of 10 amino acids were determined in four normal subjects and 18 burned patients (mean burn size, 41% of total body surface) by measuring leg blood flow by venous occlusion plethysmography and arterial (A) and femoral venous (FV) amino acid concentrations. Patient arterial plasma amino acid concentrations generally were low or normal, although phenylalanine was elevated. Only alanine demonstrated significant A-FV concentration difference (-9 +/- 2 mumole/100 ml in patients vs -5 +/- 1in controls, mean +/- SEM). Leg blood flow was 6.26 +/- 0.57 ml/100 ml of leg volume . min in the patients and 2.62 +/- 0.57 in controls. While the net peripheral release of the 10 amino acids was accelerated following injury, only alanine release was consistently greater in the patients (0.27 plus or minus 0.05 mumole/100 ml in leg volume . min) as compared with that of controls (0.08 +/- 0.02). The increased alanine release from legs of patients generally was related to the extent of total body surface injury and oxygen consumption of the patient, but was unrelated to size of limb burn or leg blood flow. The accelerated rate of alanine release from limbs of burn patients relates to the generalized catabolic effects of injury rather than to local inflammatory or metabolic events which may occur in the injured extremity.