Enteral glutamate is the preferential source for mucosal glutathione synthesis in fed piglets.
To measure the source and rate of mucosal glutathione (GSH) synthesis, fed piglets (28 days old; 7.7 kg) received a 6-h infusion of intragastric [U-13C]glutamate (n = 11) either with (n = 5) or without (n = 6) an intragastric infusion of [1-13C]glycine (0-6 h) and [1,2-13C2(U-13C)]glycine (3-6 h). Eighty-four percent of the labeled mucosal GSH-glutamate and 86% of the luminal GSH-glutamate was 13C5. The tracer-to-tracee ratio of GSH-[U-13C]glutamate was 75% of that of mucosal glutamate. Sixty percent of the labeled mucosal glutamate was 13C1, 13C2, or 13C3, but the tracer-to-tracee ratios of these isotopomers in GSH-glutamate were not significantly different from zero. After 3 h of infusion, the tracer-to-tracee ratio of GSH-[U-13C]glycine was 46%, and after 6 h of infusion GSH-[13C1]glycine was 82% of that of mucosal glycine. This suggested that the half-life of mucosal GSH was 2.7 +/- 0.1 h. We concluded that, in fed piglets, mucosal GSH-glutamate derived largely from the direct metabolism of enteral glutamate rather than from glutamate that was metabolized within the mucosa.
Reeds
P J
PJ
United States Department of Argriculture/Agriculture Research Service Children's Nutrition Research Center, Houston, Texas, USA.
Burrin
D G
DG
Stoll
B
B
Jahoor
F
F
Wykes
L
L
Henry
J
J
Frazer
M E
ME
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D004435:Eating; D018698:Glutamic Acid / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D005978:Glutathione / Q000096:biosynthesis*; D005998:Glycine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D007441:Intubation, Gastrointestinal; D013552:Swine / Q000378:metabolism*
D018698:Glutamic Acid; D005978:Glutathione; D005998:Glycine