Effect of intravenous amino acids on glutamine and protein kinetics in low-birth-weight preterm infants during the immediate neonatal period

Mark M. Kadrofske, Prabhu Parimi, Lourdes L. Gruca, Satish C. Kalhan

Research output: Contribution to journalArticle

Abstract

Glutamine may be a conditionally essential amino acid in low-birth-weight (LBW) preterm neonates. Exogenously administered amino acids, by providing anaplerotic carbon into the tricarboxylic acid cycle, could result in greater cataplerotic efflux and glutamine de novo synthesis. The effect of dose and duration of amino acid infusion on glutamine and nitrogen (N) kinetics was examined in LBW infants in the period immediately after birth. Preterm neonates (-1·h-1 of an intravenous amino acid solution for 19-24 hours, followed by a higher or lower amino acid load for either 5 h or 24 h. Glutamine de novo synthesis, leucine N, phenylalanine, and urea kinetics were determined using stable isotopic tracers. An increase in amino acid infusion from 480 to 960 μmol·kg-1·h-1 for 5 h resulted in decreased glutamine de novo synthesis in every neonate (384.4 ± 38.0 to 368.9 ± 38.2 μmol·kg-1·h-1, P <0.01) and a lower whole body rate of proteolysis (P <0.001) and urea synthesis (P <0.001). However, when the increased amino acid infusion was extended for 24 h, glutamine de novo synthesis increased (369.7 ± 92.6 to 483.4 <97.5 μmol·kg-1·h-1, P <0.001), whole body rate of proteolysis did not change, and urea production increased. Decreasing the amino acid load resulted in a decrease in glutamine rate of appearance (Ra) and leucine N Ra, but had no effect on phenylalanine Ra. Acutely stressed LBW infants responded to an increase in amino acid load by transiently suppressing whole body rate of glutamine synthesis, proteolysis, and oxidation of protein. The mechanisms of this transient effect on whole body protein/nitrogen metabolism remain unknown.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume290
Issue number4
DOIs
StatePublished - Apr 2006

Fingerprint

Low Birth Weight Infant
Glutamine
Premature Infants
Amino Acids
Kinetics
Proteolysis
Proteins
Urea
Newborn Infant
Phenylalanine
Leucine
Nitrogen
Essential Amino Acids
Citric Acid Cycle
Metabolism
Carbon
Parturition
Oxidation

Keywords

  • Glutamine metabolism
  • Neonates
  • Protein metabolism
  • Stable isotope tracers
  • Very low birth weight

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Biochemistry

Cite this

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title = "Effect of intravenous amino acids on glutamine and protein kinetics in low-birth-weight preterm infants during the immediate neonatal period",
abstract = "Glutamine may be a conditionally essential amino acid in low-birth-weight (LBW) preterm neonates. Exogenously administered amino acids, by providing anaplerotic carbon into the tricarboxylic acid cycle, could result in greater cataplerotic efflux and glutamine de novo synthesis. The effect of dose and duration of amino acid infusion on glutamine and nitrogen (N) kinetics was examined in LBW infants in the period immediately after birth. Preterm neonates (-1·h-1 of an intravenous amino acid solution for 19-24 hours, followed by a higher or lower amino acid load for either 5 h or 24 h. Glutamine de novo synthesis, leucine N, phenylalanine, and urea kinetics were determined using stable isotopic tracers. An increase in amino acid infusion from 480 to 960 μmol·kg-1·h-1 for 5 h resulted in decreased glutamine de novo synthesis in every neonate (384.4 ± 38.0 to 368.9 ± 38.2 μmol·kg-1·h-1, P <0.01) and a lower whole body rate of proteolysis (P <0.001) and urea synthesis (P <0.001). However, when the increased amino acid infusion was extended for 24 h, glutamine de novo synthesis increased (369.7 ± 92.6 to 483.4 <97.5 μmol·kg-1·h-1, P <0.001), whole body rate of proteolysis did not change, and urea production increased. Decreasing the amino acid load resulted in a decrease in glutamine rate of appearance (Ra) and leucine N Ra, but had no effect on phenylalanine Ra. Acutely stressed LBW infants responded to an increase in amino acid load by transiently suppressing whole body rate of glutamine synthesis, proteolysis, and oxidation of protein. The mechanisms of this transient effect on whole body protein/nitrogen metabolism remain unknown.",
keywords = "Glutamine metabolism, Neonates, Protein metabolism, Stable isotope tracers, Very low birth weight",
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T1 - Effect of intravenous amino acids on glutamine and protein kinetics in low-birth-weight preterm infants during the immediate neonatal period

AU - Kadrofske, Mark M.

AU - Parimi, Prabhu

AU - Gruca, Lourdes L.

AU - Kalhan, Satish C.

PY - 2006/4

Y1 - 2006/4

N2 - Glutamine may be a conditionally essential amino acid in low-birth-weight (LBW) preterm neonates. Exogenously administered amino acids, by providing anaplerotic carbon into the tricarboxylic acid cycle, could result in greater cataplerotic efflux and glutamine de novo synthesis. The effect of dose and duration of amino acid infusion on glutamine and nitrogen (N) kinetics was examined in LBW infants in the period immediately after birth. Preterm neonates (-1·h-1 of an intravenous amino acid solution for 19-24 hours, followed by a higher or lower amino acid load for either 5 h or 24 h. Glutamine de novo synthesis, leucine N, phenylalanine, and urea kinetics were determined using stable isotopic tracers. An increase in amino acid infusion from 480 to 960 μmol·kg-1·h-1 for 5 h resulted in decreased glutamine de novo synthesis in every neonate (384.4 ± 38.0 to 368.9 ± 38.2 μmol·kg-1·h-1, P <0.01) and a lower whole body rate of proteolysis (P <0.001) and urea synthesis (P <0.001). However, when the increased amino acid infusion was extended for 24 h, glutamine de novo synthesis increased (369.7 ± 92.6 to 483.4 <97.5 μmol·kg-1·h-1, P <0.001), whole body rate of proteolysis did not change, and urea production increased. Decreasing the amino acid load resulted in a decrease in glutamine rate of appearance (Ra) and leucine N Ra, but had no effect on phenylalanine Ra. Acutely stressed LBW infants responded to an increase in amino acid load by transiently suppressing whole body rate of glutamine synthesis, proteolysis, and oxidation of protein. The mechanisms of this transient effect on whole body protein/nitrogen metabolism remain unknown.

AB - Glutamine may be a conditionally essential amino acid in low-birth-weight (LBW) preterm neonates. Exogenously administered amino acids, by providing anaplerotic carbon into the tricarboxylic acid cycle, could result in greater cataplerotic efflux and glutamine de novo synthesis. The effect of dose and duration of amino acid infusion on glutamine and nitrogen (N) kinetics was examined in LBW infants in the period immediately after birth. Preterm neonates (-1·h-1 of an intravenous amino acid solution for 19-24 hours, followed by a higher or lower amino acid load for either 5 h or 24 h. Glutamine de novo synthesis, leucine N, phenylalanine, and urea kinetics were determined using stable isotopic tracers. An increase in amino acid infusion from 480 to 960 μmol·kg-1·h-1 for 5 h resulted in decreased glutamine de novo synthesis in every neonate (384.4 ± 38.0 to 368.9 ± 38.2 μmol·kg-1·h-1, P <0.01) and a lower whole body rate of proteolysis (P <0.001) and urea synthesis (P <0.001). However, when the increased amino acid infusion was extended for 24 h, glutamine de novo synthesis increased (369.7 ± 92.6 to 483.4 <97.5 μmol·kg-1·h-1, P <0.001), whole body rate of proteolysis did not change, and urea production increased. Decreasing the amino acid load resulted in a decrease in glutamine rate of appearance (Ra) and leucine N Ra, but had no effect on phenylalanine Ra. Acutely stressed LBW infants responded to an increase in amino acid load by transiently suppressing whole body rate of glutamine synthesis, proteolysis, and oxidation of protein. The mechanisms of this transient effect on whole body protein/nitrogen metabolism remain unknown.

KW - Glutamine metabolism

KW - Neonates

KW - Protein metabolism

KW - Stable isotope tracers

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