190 Increased Parenteral Amino Acid Infusion has only a Transient Effect on Whole Body Rate of Proteolysis and De Novo Glutamine Synthesis in LBW Infants

Abstract

Early administration of parenteral nutrition to LBW infants has been advocated in order to (a) meet the nutrient needs and (b) achieve intrauterine growth velocity. We have examined the impact of high parenteral amino acids on whole body protein/nitrogen turnover in low birth weight infants (<1500g, <32 weeks gestation) at <48 h and at 3–5 d after birth. Phenylalanine, glutamine, leucine N and urea turnover were measured using stable isotopic tracers while the infants were receiving parenteral amino acids at 1.5 g.kg-1.d-1 for 24h and when receiving 3.0 g.kg-1.d-1 either for 5h or for 20h. Protein breakdown (phenylalanine Ra) decreased when amino acid at 3.0 g.kg-1.d-1 were infused for 5h and then reverted back to basal state at 20h. The associated decrease in urea Ra was also transient. High amino acid load and thus increased anaplerotic flux caused a significant increase in leucine N Ra and de novo glutamine synthesis. Conclusion: Amino acid load only has a transient impact on whole body protein turnover. Additional intervention strategies need to be developed in order to achieve a growth-promoting effect of such interventions.