Intestinal metabolism of orally administered glucose and fructose in Yucatan miniature swine.
Absorption rates and metabolism of orally administered glucose and fructose were quantitated in conscious, overnight-fasted, Yucatan miniature swine. The pigs were surgically prepared, with catheters in the portal vein and a carotid artery. A continuous wave Doppler flow cuff was placed around the portal vein. Four to 7 days after surgery, arterial and portal venous blood samples were obtained in the basal state and at 15-minute intervals for 4 hours following oral administration of glucose or fructose (1.5 g/kg body weight). Absorption rates and intestinal metabolism were calculated from portal blood flow and arterio-venous concentration differences for glucose, fructose and lactate. Oral fructose administration was accompanied by a rise in intestinal lactate production, which correlated significantly with the fructose absorption rate. Intestinal lactate output during fructose absorption could account for 12% of the fructose absorbed or metabolized. A small rise in glucose output from the gut was also observed. In contrast, after oral glucose administration, only a modest rise in intestinal lactate output was noted. It could account for only 2% of the glucose absorbed or metabolized. No correlation between glucose absorption rate and intestinal lactate output was observed. These studies indicate that a significant portion of oral fructose is converted to lactate during absorption but that the major part enters the portal vein as fructose. Only minimal intestinal metabolism of ingested glucose occurs.
D000284:Administration, Oral; D000818:Animals; D005632:Fructose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D013552:Swine; D013556:Swine, Miniature
D007773:Lactates; D005632:Fructose; D005947:Glucose