Rate of [15N]leucine incorporation and determination of nitrogenous fractions from gastro-jejunal secretion in fasting humans.
The aim of this study was to quantify the nitrogen fraction flow rates in gastro-jejunal secretions in fasting humans and to determine the [15N]leucine incorporation into the secreted proteins. A double lumen intestinal perfusion method was used in 5 healthy volunteers. Plasma and gastro-jejunal juices were collected during a 15-h intravenous [15N]leucine infusion. Total, soluble and insoluble nitrogen, amino acids and [15N]leucine enrichment were measured. The total nitrogen flow rate was 7.2 +/- 1.9 mmol.h-1 and 58% was ethanol soluble. The amino-acid composition remained constant and glycine was the most abundant. The plasma [15N]leucine enrichment at the isotopic plateau was 4.8 +/- 0.9 mol% excess. The [15N]leucine enrichment in the intestinal chyme increased asymptotically to reach a plateau after 5 h. The [15N]leucine enrichment at the plateau and the fractional synthesis rate of secreted proteins were 1.6 +/- 0.5 mol% excess and 21.5 +/- 3.3%.h-1, respectively. These results show that the composition of the basal gastro-jejunal secretion is very stable. A part of this secretion is composed of proteins with rapid synthesis rates.
Gaudichon
C
C
INRA, Unité de Nutrition Humaine et de Physiologie Intestinale, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France.
Laurent
C
C
Mahé
S
S
Marks
L
L
Tomé
D
D
Krempf
M
M
D000328:Adult; D005215:Fasting / Q000378:metabolism*; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism; D006801:Humans; D007583:Jejunum / Q000378:metabolism*; D007930:Leucine / Q000493:pharmacokinetics*; D008297:Male; D009584:Nitrogen / Q000493:pharmacokinetics*; D009587:Nitrogen Isotopes; D011506:Proteins / Q000378:metabolism*
D009587:Nitrogen Isotopes; D011506:Proteins; D007930:Leucine; D009584:Nitrogen; D005998:Glycine