Role of Glutamine and Its Analogs in Posttraumatic Muscle Protein and Amino Acid Metabolism

Abstract

Skeletal muscle protein catabolism following trauma has until recently not been possible to counteract by intravenous nutritional means. The obligatory loss of nitrogen with concomitant reduction of skeletal muscle protein synthesis is also accompanied by a decrease of muscle free glutamine, the extent of which is proportional to the muscle protein catabolism. Serving as a human model of surgical trauma, patients undergoing elective cholecystectomy were given total parenteral nutrition including additions of either glutamine or its analogs (ornithine-alpha-ketoglutarate, alpha-ketoglutarate, or alanylglutamine) during 3 postoperative days. The polyribosome concentration and the intracellular glutamine concentration in skeletal muscle, as well as nitrogen balance, showed a less pronounced skeletal muscle catabolism in these groups than when conventional total parenteral nutrition was given. It is concluded that a support of either glutamine or its carbon skeleton, alpha-ketoglutarate, counteracts the postoperative fall of muscle free glutamine and of muscle protein synthesis. Furthermore, statistical correlations could be shown between the changes of muscle glutamine and muscle protein synthesis and the postoperative nitrogen losses.