Total-body protein turnover in parenterally fed neonates: effects of energy source studied by using [15N]glycine and [1-13C]leucine.
The effects of nonprotein energy source (ie, glucose only vs glucose and lipid) on nitrogen retention and total-body protein turnover were studied in 20 parenterally fed newborn infants. All infants received approximately 3 g amino acids and 80-90 kcal.kg body wt.d. Total-body protein synthesis was estimated by using three constant-infusion, end-product methods: enrichment of urinary urea and ammonia in response to a [15N]glycine label and exhaled carbon dioxide enrichment in response to a [1-13C]leucine label. No differences were seen in nitrogen retention between the two energy sources. The estimate of total-body protein turnover obtained from the 13C label was similar to that obtained with the [15N]urea label. No differences in turnover rates were observed between the two diet groups. Use of the glucose-plus-lipid fuel system enhanced energy storage and the reutilization of amino acid for protein synthesis.
Pencharz
P
P
Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
Beesley
J
J
Sauer
P
P
Van Aerde
J
J
Canagarayar
U
U
Renner
J
J
McVey
M
M
Wesson
D
D
Swyer
P
P
D000641:Ammonia / Q000652:urine; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D002149:Energy Intake; D004734:Energy Metabolism; D005217:Fat Emulsions, Intravenous / Q000008:administration & dosage / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn / Q000378:metabolism*; D007930:Leucine / Q000008:administration & dosage / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D009587:Nitrogen Isotopes; D010288:Parenteral Nutrition; D011506:Proteins / Q000378:metabolism*; D014508:Urea / Q000652:urine
D002247:Carbon Isotopes; D005217:Fat Emulsions, Intravenous; D009587:Nitrogen Isotopes; D011506:Proteins; D002245:Carbon Dioxide; D000641:Ammonia; D014508:Urea; D007930:Leucine; D005947:Glucose; D009584:Nitrogen; D005998:Glycine