Effects of varying levels of duodenal or midjejunal glucose and 2-deoxyglucose infusion on small intestinal disappearance and net portal glucose flux in steers.
Six crossbred steers (261 +/- 18 kg BW) fitted with hepatic portal, mesenteric venous and arterial catheters, and duodenal, midjejunal, and ileal cannulas were used in a replicated 3 x 3 Latin square design to determine the effect of varying levels and site of glucose plus 2-deoxyglucose (2DG) infusion on net portal-drained visceral flux. Steers were fed chopped alfalfa in six equal portions daily at 1.5% of BW. Glucose (0, 9, or 18 g/h) and 2DG (0, 1, or 2 g/h) were infused continuously through the duodenal or midjejunal cannula (two infusion sites) at total glucose plus 2DG infusion rates of 0, 10, or 20 g/h. Arterial and portal blood samples were taken simultaneously at 20-min intervals from 5 to 9 h of infusion. Portal blood flow was determined by continuous infusion of p-aminohippurate and net flux was calculated as venous-arterial concentration (PA) difference times blood flow. Arterial concentration of glucose was not affected (P > .10) by glucose plus 2DG infusion, whereas arterial concentration of 2DG was greater (P < .05) when glucose plus 2DG was infused into the duodenum and increased (linear, P < .10) as amount of glucose plus 2DG infused into both the duodenum and midjejunum increased. Net portal flux and PA difference of glucose and 2DG were greater (P < .05) when glucose plus 2DG was infused into the duodenum. Although 2DG was infused at 10% of the total glucose plus 2DG infusion, it accounted for only 1.7 and .7% of the glucose plus 2DG appearing in portal blood when glucose plus 2DG was infused at 10 and 20 g/h, respectively. We conclude that glucose is more readily absorbed across the proximal-half than the distal-half of the small intestine, and that passive diffusion is a minor route of glucose absorption.
Krehbiel
C R
CR
University of Nebraska, Lincoln 68583, USA.
Britton
R A
RA
Harmon
D L
DL
Peters
J P
JP
Stock
R A
RA
Grotjan
H E
HE
D000818:Animals; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism; D002417:Cattle / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D003847:Deoxyglucose / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics; D004386:Duodenum / Q000737:chemistry / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D007262:Infusions, Intravenous / Q000662:veterinary; D007408:Intestinal Absorption / Q000502:physiology*; D007583:Jejunum / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D011897:Random Allocation
D001786:Blood Glucose; D003847:Deoxyglucose; D005947:Glucose