|Burrin, Douglas - Doug|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2002
Publication Date: 11/1/2002
Citation: Lambert,B., Stoll,B., Niinikoski,H., Pierzynowski,S., Burrin,D.G. 2002. Net portal absorption of enterally fed alpha-ketoglutarate is limited in young pigs. Journal of Nutrition. 132(11):3383-3386. Interpretive Summary: Alpha-ketoglutarate (AKG) is an intermediate formed during the metabolism of the amino acid, glutamate. Because glutamate is a major fuel for the small intestine, and glutamate is converted to AKG before it is used as a fuel, we hypothesized that feeding AKG might decrease the amount of glutamate used as a fuel for the gut, thereby increasing the amount available to the remainder of the body. To test this, young pigs were fed increasing levels of dietary AKG (0%, 2.5%, 5% or 10%) over a 4-hour period. To measure the amount of dietary AKG absorbed from the gut, we collected blood samples from the artery and portal vein that drains the intestinal tract of the pigs. A maximum of 11% of the dietary AKG infused was absorbed into the portal blood. This may indicate that the AKG was either not taken up by the digestive tract, or was used within the cells of the digestive tract as a source of fuel. The release of amino acids or ammonia did not change as a result of AKG treatment. We conclude that the absorption of dietary AKG is limited in young pigs, and does not change the net portal absorption of amino acids or ammonia.
Technical Abstract: Our aim was to quantify the intestinal metabolic fate of dietary alpha-ketoglutarate (AKG). Six female pigs (21 d old) were implanted with arterial, venous, portal and gastric catheters and an ultrasonic portal flow probe and fed a corn and soybean meal based diet. On the day of the experiment, the pigs received a 4-h intragastric infusion of sodium AKG at a rate equivalent to 0, 2.5, 5, or 10% of dietary intake. The net portal AKG3 balance of the control and 2.5% treatment did not differ and were not different from zero. However, the net portal AKG balance of both the 5 (163 micromol · kg-1 · h-1) and 10% (159 micromol · kg-1 · h-1) treatments were greater (P < 0.05) than the control. Despite significant net AKG absorption at the 5% and 10% levels, the net portal appearance only represented 10.8% and 6.7%, respectively, of the enteral input. The net portal appearances of glutamate, glutamine, ammonia and the branched chain amino acids were not affected by dietary AKG level. We conclude that the absorption of dietary AKG is limited in young pigs, and does not change the net portal balance of amino acids or ammonia.