Absorption and metabolism of glucose by the mesenteric-drained viscera of sheep fed on dried-grass or ground, maize-based diets.

Sheep fitted with re-entrant canulas in the proximal duodenum and terminal ileum were used to determine the amount of alpha-glucoside entering, and apparently disappearing from, the small intestine when either dried-grass or ground maize-based diets were fed. The fate of any alpha-glucoside entering the small intestine was studied by comparing the net disappearance of such alpha-glucoside from the small intestine with the absorption of glucose into the mesenteric venous blood. Glucose absorption from the small intestine was measured in sheep equipped with catheters in the mesenteric vein and carotid artery. A continuous infusion of [6-3H]glucose was used to determine glucose utilization by the mesenteric-drained viscera and the whole-body glucose turnover rate (GTR). The amounts of alpha-glucoside entering the small intestine when the dried-grass and maize-based diets were given were 13.9 (SE 1.5) and 95.4 (SE 16.2) g/24 h respectively; apparent digestibilities of such alpha-glucoside in the small intestine were 60 and 90% respectively. The net absorption of glucose into the mesenteric venous blood was -2.03 (SE 1.20) and 19.28 (SE 0.75) mmol/h for the dried-grass and maize-based diets respectively. Similarly, total glucose absorption amounted to 1.52 (SE 1.35) and 23.33 (SE 1.86) mmol/h (equivalent to 7 and 101 g/24 h respectively). These values represented 83 and 111% of the alpha-glucoside apparently disappearing from the small intestine, determined using the re-entrant cannulated sheep. Total glucose absorption represented 8 and 61% of the whole-body GTR for the dried-grass and maize-based diets respectively.(ABSTRACT TRUNCATED AT 250 WORDS)