1. The effect of thermal injury (33–35% of body surface area) on the regulation of glutamine metabolism was studied in skeletal muscles of rats 7 days after injury.
2. Injury increased the rates of glutamine production in muscle, skin and adipose tissue preparations, with muscle production accounting for over 90% of total glutamine produced by the hindlimb.
3. Injury produced decreases in the concentrations of skeletal muscle glutamine (36%, P < 0.001), glutamate (39%, P < 0.001), alanine (24%, P < 0.001), pyruvate (35%, P < 0.001), 2-oxoglutarate (51%, P < 0.001) and adenosine 5′-triphosphate (38%, P < 0.001). The concentrations of ammonia (42%, P < 0.001) and inosine 5′-phosphate (430%, P < 0.001) were increased.
4. The maximal activity of glutamine synthetase was increased (22–40%, P < 0.001) in muscles of injured rats, whereas that of glutaminase was unchanged.
5. Hindlimb blood flow decreased by approximately 15% in injured rats, which was accompanied by an enhanced net release of glutamine (80%, P < 0.001) and alanine (44%, P < 0.001).
6. It is concluded that there is an enhanced rate of release of both glutamine and alanine from skeletal muscle of thermally injured rats. This may be due to changes in efflux and/or increased intracellular formation of glutamine and alanine.