Enhanced amino acid uptake in both skeletal muscle and liver by burn plasma in rats.

The study was designed to test amino acid uptake in skeletal muscle after burn injury (up to 72 h). Also examined were the effects of plasma from burned rats over varying periods postburn (1-72 h), when plasma was added in vitro to incubated muscles and liver slices. Major burn injury (40 per cent total body surface area (TBSA)) was produced in male Sprague-Dawley rats weighing 60-80 g. Both soleus muscles were dissected intact at 1, 3, 6, 12, 24, 48 and 72 h postburn. Amino acid transport was measured by determining intracellular uptake of [3H] alpha-aminoisobutyric acid (AIB) during a 2 h incubation. In the second series of experiments, whole plasma from burned rats was added in vitro to incubated muscles and liver slices from healthy animals, and amino acid uptake was determined. AIB uptake in burned rat muscle was reduced by 24 per cent by 24 h postburn and 16 per cent by 48 h postburn. There was an increased effect from burn plasma on normal incubated muscles and liver slices, 72 per cent on muscles and 30 per cent on livers. Present results suggest an intrinsic decrease in amino acid uptake by muscle from burned rats. A factor or factors existed in plasma which increased both muscle and liver amino acid uptake postburn.