The effect of glutamine- and alanine-enriched total parenteral nutrition on postburn proteolysis in the rat

This study compared the effects of total parenteral nutrition (TPN) supplemented with either glutamine (GLN) or alanine (ALA) on postburn proteolysis in the rat. Thirty adult Sprague-Dawley rats underwent catheterization of the superior vena cava and placement of a swivel apparatus. One group (CONTROL, N = 18) was then returned to their cages while the remaining animals (BURN, N = 12) received a full-thickness scald burn (approximately 20% BSA). CONTROL and BURN rats were then randomly assigned to receive TPN supplemented with either GLN or ALA. TPN consisted of dextrose (250 Kcal/Kg BW/day) and crystalline amino acids (0.9 gN/kg BW/day) composed of all essential amino acids, histidine, arginine, glycine, and either ALA or GLN (1.2 g/100 mg). TPN was administered for 3 days after the burn. Urinary 3-methyl histidine (3MH) and nitrogen excretions were determined, and blood amino acids were measured. Both BURN groups had significantly higher 3MH excretion and blood levels of branched chain amino acids (BCAA) and alanine than both CONTROL groups. In both BURN and CONTROL groups, GLN-TPN did not significantly affect 3MH excretion or the blood levels of BCAA or alanine compared with ALA-TPN. In BURN animals, GLN-TPN resulted in significantly higher urinary nitrogen excretion than ALA-TPN resulting in lower nitrogen retention. Compared with ALA-TPN, GLN-TPN produced greater urinary nitrogen losses and did not reduce protein catabolism.