Infusion of dipeptides as nutritional substrates for glutamine, tyrosine, and branched-chain amino acids in patients with acute pancreatitis

Abstract

In this study we investigated the effect of a total parenteral nutrition supplemented with synthetic dipeptides on plasma and muscle amino acid metabolism in four patients with acute pancreatitis. We infused an amino acid solution containing alanylglutamine, glycylglutamine, glycylvaline, glycylisoleucine, glylcylleucine, and glycyltyrosine for a period of five days in daily dosages of 10.3, 22.1, 68.8, 37.2, 42.5, and 15.7 mmol, respectively. The plasma levels remained below 100 μmol/L for all infused dipeptides. The plasma concentrations of alanylglutamine were not measurable. Mean peptide urine excretion remained below 5%, with the exception of glycylglutamine (8.5% ± 5.1%). Arteriovenous concentration differences of the dipeptides across the leg were not significantly different from zero, indicating that the infused dipeptides have no important role in the nitrogen exchange of skeletal muscle. A marked intracellular glutamine deficiency in skeletal muscle was found in all four patients (5.1 ± 0.6 mmol/L v 19.5 ± 0.8 in healthy subjects) before infusion. Intracellular glutamine concentration was significantly higher after the infusion period (5.1 ± 0.7 v 9.5 ± 1.8 mmol/L, P > .05), but no normalization of the intracellular glutamine levels was achieved by the infusion of the two glutamine-containing peptides. We conclude that peptides are well metabolized as substrates for parenteral nutrition in catabolic patients. Furthermore, the infusion of glutamine peptides caused a significant increase of intracellular glutamine levels; however, the dosage of glutamine peptides was too low to normalize the muscular glutamine concentrations.