THE POST-SCALD METABOLIC RESPONSE IN THE GROWING-RAT - EVIDENCE FOR A TRANSIENT PHASE OF MUSCLE PROTEIN BREAKDOWN

Growing male rats were studied for 16 days following a full-thickness 30 per cent body surface area dorsal scald. Weight gain post scald was reduced despite normal food intake. Evaporative weight loss increased after the injury and remained elevated. Oxygen consumption also increased and was significantly correlated with evaporative loss in injured rats although not in controls. Plasma branched-chain amino acid concentrations and urinary Nτ-methyl-histidine excretion were increased over the first 72 h after injury, and were associated with net loss of muscle protein. Plasma branched-chain amino acids fell below control levels 5-7 days after scalding as muscle protein content increased. It was concluded that a 30 per cent scald in the growing rat leads to a transient 'flow ' phase with net muscle protein breakdown, followed by a more prolonged period of hypermetabolism which is due largely to increased evaporative heat loss