Immediate Stimulation of Protein Metabolism in Burned Rats by Total Parenteral Nutrition Enriched in Branched‐Chain Amino Acids

Abstract

The effects of two kinds of total parenteral nutrition (TPN) on energy and protein metabolism were examined in rats subjected to 15% full-thickness scald burns in the absence of septic complications. One type of TPN was enriched in branched-chain amino acids (BCAAs), especially leucine (45% BCAA content), and the other was conventional TPN (21% BCAA content). Burned rats received isocaloric and isonitrogeneous TPN solutions for 48 hr after resuscitation by saline infusion for 24 hr. Liver and rectus abdominis muscle were removed from the rats at 7, 24, 48, and 72 hr. The concentrations of adenine nucleotides, RNA, protein, glucose-6-phosphate, hepatic glycogen, muscle phosphocreatine, and 3-methylhistidine were determined. Metabolic alterations occurred during the period of saline resuscitation (0-24 hr). At 48 hr the RNA and protein levels were significantly more improved in the BCAA-TPN group than in the conventional TPN group. At 72 hr, however, the results for the two groups were similar in most metabolite levels. Thus, BCAA-TPN enriched in leucine rapidly stimulated protein synthesis in the liver and muscle. This rapid effect may make it useful during the initial nutritional management of severe trauma patients.

Protein Metabolism and Therapy in Burn Injury

“…Experimentally, branched-chain AAs have been shown to promote protein synthesis and reduce protein catabolism [99] and, in the burned rat [100], to stimulate protein synthe sis in liver and muscle. However, the clinical relevance of branched-chain supplementation remains speculative as suggested by studies in burn patients showing a reduction in 3MH excretion without improvement in nitrogen balance [101,102] or no advantage [103], As stated above, hypercatabolic and hypermetabolic situations are accompanied by se vere glutamine deprivation mainly caused by trauma-induced alterations in the interorgan glutamine flow.…”