Absorption of alpha-ketoglutarate by the gastrointestinal tract of pigs.
Only a small percentage of alpha-ketoglutarate (AKG) administered lumenally to pigs appears in the portal circulation. This has been attributed to mucosal metabolism, and possibly by limited absorption. Although transporters for di- and tricarboxylic acids, which includes the sodium-dependent transporter NaDC-1, have been detected in the small intestine, correlations with functional assays are lacking. Therefore, intact tissues from three regions of the small intestine, stomach, and colon of weaned pigs were used to measure rates of AKG absorption. Western analysis was used to detect NaDC-1 in the three regions of small intestine. Rates of AKG absorption were highest in the small intestine, lowest in the colon, and intermediate in the stomach. Immunoreactive NaDC-1 was detected in the small intestine and this coincided with a component of AKG absorption that was inhibited by AKG and succinate. In contrast, absorption of AKG was inhibitable by unlabeled AKG, but not succinate, in the stomach, and by neither in the colon. Feeding studies indicated that the amounts of AKG that might be included in practical diets for pigs would not (1) upregulate rates of AKG absorption or (2) exceed estimated capacities of the small intestine to absorb AKG. The present findings indicate that the efficacy of AKG as an alternative metabolic fuel for enterocytes to spare dietary amino acids is not limited by absorption.
Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA. rkb1@ra.msstate.edu
Randal K
RK
Buddington
Ana
A
Pajor
Karyl K
KK
Buddington
Stefan
S
Pierzynowski
D000042:Absorption; D000818:Animals; D015153:Blotting, Western; D003106:Colon / Q000502:physiology; D041981:Gastrointestinal Tract / Q000502:physiology*; D007408:Intestinal Absorption / Q000502:physiology*; D007421:Intestine, Small / Q000502:physiology; D007656:Ketoglutaric Acids / Q000737:chemistry* / Q000493:pharmacokinetics*; D013270:Stomach / Q000502:physiology; D013552:Swine; D014018:Tissue Distribution
D007656:Ketoglutaric Acids