Effect of enteral glutamine or glycine on whole-body nitrogen kinetics in very-low-birth-weight infants

• Published in: The American journal of clinical nutrition Vol. 79; no. 3; pp. 402 - 409
• Main Authors: PARIMI, Prabhu S, DEVAPATLA, Srisatish, GRUCA, Lourdes L, AMINI, Saeid B, HANSON, Richard W, KALHAN, Satish C
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.03.2004; American Society for Clinical Nutrition, Inc
• Subjects: Babies; Biological and medical sciences; Birth weight; Blood Urea Nitrogen; Enteral Nutrition; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Glutamine - administration & dosage; Glutamine - blood; Glutamine - pharmacokinetics; Glycine - administration & dosage; Glycine - blood; Glycine - pharmacokinetics; Humans; Infant Formula; Infant Nutritional Physiological Phenomena; Infant, Newborn; Infant, Very Low Birth Weight - blood; Infant, Very Low Birth Weight - growth & development; Infant, Very Low Birth Weight - metabolism; Kinetics; Leucine - blood; Leucine - pharmacokinetics; Nitrogen; Nitrogen - pharmacokinetics; Urea - pharmacokinetics; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Premature; premature infants; reamination; Pregnancy disorders; Phenylalanine; Growth; Infant; Leucine; Nitrogen; Glycine; Very low birthweight; Urea; Newborn diseases; Prematurity; Neurotransmitter; Kinetics; Whole body; Glutamine
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/79.3.402

Glutamine is a critical amino acid for the metabolism of enterocytes, lymphocytes, and other proliferating cells. Although supplementation with glutamine has been suggested for growing infants, its effect on protein metabolism has not been examined. The objective was to examine the effect of enteral glutamine or glycine on whole-body kinetics of glutamine, phenylalanine, leucine, and urea in preterm infants. Infants at <32 wk of gestation were given formula supplemented with either glutamine (0.6 g. kg(-1). d(-1); n = 9) or isonitrogenous amounts of glycine (n = 9) for 5 d. Eight infants fed unsupplemented formula served as control subjects. Glutamine, phenylalanine, leucine nitrogen flux, leucine carbon flux, and urea kinetics were quantified during a basal fasting period and in response to nutrient intake. Growing preterm infants had a high weight-specific rate of appearance of glutamine, phenylalanine, and leucine nitrogen flux. When compared with the control treatment, enteral glutamine resulted in a high rate of urea synthesis, no change in the plasma glutamine concentration, and no change in the rate of appearance of glutamine. Glycine supplementation resulted in similar changes in nitrogen metabolism, but the magnitude of change was less than that in the glutamine group. In the nonsupplemented infants, the rate of appearance of leucine nitrogen flux was negatively correlated (rho = -0.72) with urea synthesis. In contrast, the correlation (rho = 0.75) was positive in the glutamine group. Enterally administered glutamine in growing preterm infants is entirely metabolized in the gut and does not have a discernable effect on whole-body protein and nitrogen kinetics.