AJP - Endocrinology and Metabolism, Vol 270, Issue 3 E413-E418, Copyright © 1996 by American Physiological Society

ARTICLES

Enteral glutamate is almost completely metabolized in first pass by the gastrointestinal tract of infant pigs

P. J. Reeds, D. G. Burrin, F. Jahoor, L. Wykes, J. Henry and E. M. Frazer
epartment of Pediatrics, United States Department of Agriculture, Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA.

We studied the absorption of enteral glutamate and phenylalanine using isotopic tracer and arteriovenous difference techniques. Six piglets, implanted with portal, carotid, and gastric catheters and an ultrasonic portal flow probe received a 6-h intragastric infusion of [U-13C] glutamate and [2H] phenylalanine, with a high-protein diet offered one time each hour. Amino acid concentrations and the isotopic enrichments of all mass isotopomers of glutamate, glutamine, and phenylalanine were measured in portal and arterial blood over the last hour. There was significant (P<0.025) net absorption of the indispensable amino acids as well as arginine, proline, serine, and alanine. There was no portal uptake of glutamate, aspartate, and glycine, and arterial glutamine was removed by the portal drained viscera (P<0.05). At isotopic steady state, 72% of the [2H] phenylalanine but only 5% of the [U-13C] glutamate tracer appeared in the portal blood. We conclude that, in fed infant pigs, the gut metabolizes virtually all of the enteral glutamate during absorption. Therefore, glutamate and glutamine in the body as a whole must derive almost entirely from synthesis de novo.

This article has been cited by other articles:

				K. L. Urschel, M. Rafii, P. B. Pencharz, and R. O. Ball A multitracer stable isotope quantification of the effects of arginine intake on whole body arginine metabolism in neonatal piglets Am J Physiol Endocrinol Metab, September 1, 2007; 293(3): E811 - E818. [Abstract] [Full Text] [PDF]

				G. K. Law, R. F. Bertolo, A. Adjiri-Awere, P. B. Pencharz, and R. O. Ball Adequate oral threonine is critical for mucin production and gut function in neonatal piglets Am J Physiol Gastrointest Liver Physiol, May 1, 2007; 292(5): G1293 - G1301. [Abstract] [Full Text] [PDF]

				M. Z. Fan, J. C. Matthews, N. M. P. Etienne, B. Stoll, D. Lackeyram, and D. G. Burrin Expression of apical membrane L-glutamate transporters in neonatal porcine epithelial cells along the small intestinal crypt-villus axis Am J Physiol Gastrointest Liver Physiol, August 1, 2004; 287(2): G385 - G398. [Abstract] [Full Text] [PDF]

				D. M. Cohen, P. H. Guthrie, X. Gao, R. Sakai, and H. Taegtmeyer Glutamine cycling in isolated working rat heart Am J Physiol Endocrinol Metab, December 1, 2003; 285(6): E1312 - E1316. [Abstract] [Full Text] [PDF]

				O. Le Bacquer, C. Laboisse, and D. Darmaun Glutamine preserves protein synthesis and paracellular permeability in Caco-2 cells submitted to "luminal fasting" Am J Physiol Gastrointest Liver Physiol, June 9, 2003; 285(1): G128 - G136. [Abstract] [Full Text] [PDF]

				M. Watford Net Interorgan Transport of L-Glutamate in Rats Occurs via the Plasma, Not via Erythrocytes J. Nutr., May 1, 2002; 132(5): 952 - 956. [Abstract] [Full Text] [PDF]

				O. Le Bacquer, H. Nazih, H. Blottiere, D. Meynial-Denis, C. Laboisse, and D. Darmaun Effects of glutamine deprivation on protein synthesis in a model of human enterocytes in culture Am J Physiol Gastrointest Liver Physiol, December 1, 2001; 281(6): G1340 - G1347. [Abstract] [Full Text] [PDF]

				C. Morens, C. Gaudichon, G. Fromentin, A. Marsset-Baglieri, A. Bensaid, C. Larue-Achagiotis, C. Luengo, and D. Tome Daily delivery of dietary nitrogen to the periphery is stable in rats adapted to increased protein intake Am J Physiol Endocrinol Metab, October 1, 2001; 281(4): E826 - E836. [Abstract] [Full Text] [PDF]

				P. J. Reeds and D. G. Burrin Glutamine and the Bowel J. Nutr., September 1, 2001; 131(9): 2505S - 2508. [Abstract] [Full Text] [PDF]

				C. Morens, C. Gaudichon, C. C. Metges, G. Fromentin, A. Baglieri, P. C. Even, J.-F. Huneau, and D. Tomé A High-Protein Meal Exceeds Anabolic and Catabolic Capacities in Rats Adapted to a Normal Protein Diet J. Nutr., September 1, 2000; 130(9): 2312 - 2321. [Abstract] [Full Text]

				A. Mordrelle, E. Jullian, C. Costa, E. Cormet-Boyaka, R. Benamouzig, D. Tome, and J.-F. Huneau EAAT1 is involved in transport of L-glutamate during differentiation of the Caco-2 cell line Am J Physiol Gastrointest Liver Physiol, August 1, 2000; 279(2): G366 - G373. [Abstract] [Full Text] [PDF]

				P. J. Reeds Dispensable and Indispensable Amino Acids for Humans J. Nutr., July 1, 2000; 130(7): 1835S - 1840. [Abstract] [Full Text]

				A. H. Forslund, L. Hambraus, H. van Beurden, U. Holmback, A. E. El-Khoury, G. Hjorth, R. Olsson, M. Stridsberg, L. Wide, T. Akerfeldt, et al. Inverse relationship between protein intake and plasma free amino acids in healthy men at physical exercise Am J Physiol Endocrinol Metab, May 1, 2000; 278(5): E857 - E867. [Abstract] [Full Text] [PDF]

				C. C. Metges, Y.-M. Yu, W. Cai, X.-M. Lu, S. Wong, M. M. Regan, A. Ajami, and V. R. Young Oxoproline kinetics and oxoproline urinary excretion during glycine- or sulfur amino acid-free diets in humans Am J Physiol Endocrinol Metab, May 1, 2000; 278(5): E868 - E876. [Abstract] [Full Text] [PDF]

				M. Haisch, N. K. Fukagawa, and D. E. Matthews Oxidation of glutamine by the splanchnic bed in humans Am J Physiol Endocrinol Metab, April 1, 2000; 278(4): E593 - E602. [Abstract] [Full Text] [PDF]

				P. J. Reeds, D. G. Burrin, B. Stoll, and F. Jahoor Intestinal Glutamate Metabolism J. Nutr., April 1, 2000; 130(4): 978 - 978. [Abstract] [Full Text]

				J. T. Brosnan Glutamate, at the Interface between Amino Acid and Carbohydrate Metabolism J. Nutr., April 1, 2000; 130(4): 988 - 988. [Abstract] [Full Text]

				P.-J. Tsai and P.-C. Huang Circadian Variations in Plasma and Erythrocyte Glutamate Concentrations in Adult Men Consuming a Diet with and without Added Monosodium Glutamate J. Nutr., April 1, 2000; 130(4): 1002 - 1002. [Abstract] [Full Text]

				V. Tanphaichitr, P. Leelahagul, and K. Suwan Plasma Amino Acid Patterns and Visceral Protein Status in Users and Nonusers of Monosodium Glutamate J. Nutr., April 1, 2000; 130(4): 1005 - 1005. [Abstract] [Full Text]

				B. Stoll, D. G. Burrin, J. Henry, H. Yu, F. Jahoor, and P. J. Reeds Substrate oxidation by the portal drained viscera of fed piglets Am J Physiol Endocrinol Metab, July 1, 1999; 277(1): E168 - E175. [Abstract] [Full Text] [PDF]

				B. Stoll, D. G. Burrin, J. F. Henry, F. Jahoor, and P. J. Reeds Dietary and systemic phenylalanine utilization for mucosal and hepatic constitutive protein synthesis in pigs Am J Physiol Gastrointest Liver Physiol, January 1, 1999; 276(1): G49 - G57. [Abstract] [Full Text] [PDF]

				G. Wu Intestinal Mucosal Amino Acid Catabolism J. Nutr., August 1, 1998; 128(8): 1249 - 1252. [Abstract] [Full Text]

				M. Pascual, F. Jahoor, and P. J. Reeds In Vivo Glucose Contribution to Glutamate Synthesis Is Maintained While Its Contribution to Acetyl CoA Is Lowered in Adult Mice Fed a Diet with a High Fat:Carbohydrate Ratio J. Nutr., April 1, 1998; 128(4): 733 - 739. [Abstract] [Full Text]

				B. Stoll, J. Henry, P. J. Reeds, H. Yu, F. Jahoor, and D. G. Burrin Catabolism Dominates the First-Pass Intestinal Metabolism of Dietary Essential Amino Acids in Milk Protein-Fed Piglets J. Nutr., March 1, 1998; 128(3): 606 - 614. [Abstract] [Full Text]

				B. Stoll, D. G. Burrin, J. Henry, F. Jahoor, and P. J. Reeds Phenylalanine utilization by the gut and liver measured with intravenous and intragastric tracers in pigs Am J Physiol Gastrointest Liver Physiol, December 1, 1997; 273(6): G1208 - G1217. [Abstract] [Full Text] [PDF]

				J. B. van Goudoever, B. Stoll, J. F. Henry, D. G. Burrin, and P. J. Reeds Adaptive regulation of intestinal lysine metabolism PNAS, October 10, 2000; 97(21): 11620 - 11625. [Abstract] [Full Text] [PDF]