Sodium glucose-linked transport in the ruminal epithelium of fallow deer -- comparison to sheep

A higher expression of the sodium glucose-linked transporter, SGLT-1, has been previously demonstrated in the intestine of adult fallow deer compared to sheep. The functional presence of SGLT-1 in the rumen of both species was investigated in the present study. Isolated ruminal epithelia were incubated in Ussing chambers. D-Glucose or 3-O-methyl-alpha-D-glucose (3-OMG) were applied at 10 mmol x l-1 to the mucosal side of tissues and the changes in short-circuit current (Delta I(sc)) were recorded. Alternatively, apical uptake of [14C]-D-glucose (200 micro mol x l-1) was determined in the presence or absence of phlorizin (100 micro mol x l-1) or Na+ (115 mmol x l-1). In both species, mucosal D-glucose addition induced a larger ( P<0.05) Delta I(sc) than the mucosal addition of 3-OMG. When comparing the effects of D-glucose or 3-OMG between species, the Delta I(sc) was two-fold larger ( P<0.01) in sheep compared to fallow deer. Accordingly, phlorizin-sensitive D-glucose uptake was approximately 50% smaller ( P<0.05) in fallow deer. It is concluded that D-glucose can be absorbed via SGLT-1 from the forestomachs of both species. However, the intermediate-mixed feeding habit of fallow deer does not seem to coincide with a higher activity of the ruminal SGLT-1.