Influence of α-linked glucose on jejunal sodium-glucose co-transport activity in ruminants

Eight steers and 12 lambs were used in a completely randomized experimental design to determine the effect of partial α-amylase starch hydrolysate (SH) on small intestinal sodium-dependent glucose transport activity. Starch hydrolysate was delivered ruminally or abomasally to steers (960 g/day) and sheep (144 g/day) for 7 days. On day 7, the steers were rendered unconscious, exsanguinated and eviscerated. A 1-m section of jejunum was collected starting at the duodenojejunal flexure. Sheep were anaesthetized with pentobarbital and the second meter of small intestine (jejunum) was collected. Brush-border membrane vesicles were prepared and sodium-dependent glucose uptake activity was measured using the rapid uptake/filtration technique. Alkaline phosphatase and maltase activity was enriched by 8.2 ± 0.5- and 8.4 ± 1.2-fold in the vesicle preparation, respectively, and was not different between treatments. Abomasal SH increased (P = 0.03) the Na/glucose co-transport approximately two-fold in both cattle (47.2-114.0 ± 31.5 pmol/mg × sec) and sheep (77.4-152.0 ± 25.7 pmol mg^-1 s^-1). We conclude that Na/glucose co-transport activity by enterocytes responds to luminal α-linked glucose (from abomasal infusion) in ruminants, compared with controls. Intestinal maltase-specific activity does not respond to α-linked glucose in cattle, and decreases slightly in sheep.