Glucose is absorbed in a sodium-dependent manner from forestomach contentsof sheep

Intraruminal glucose is thought to be completely converted to short-chain f atty acids (SCFA) by symbiotic microorganisms. Nevertheless, earlier in vit ro studies evidenced the expression of the sodium glucose-linked transporte r (SGLT)-1, in the ovine ruminal epithelium. The present study aimed to det ermine whether the ruminal SGLT-1 is functionally important in vivo. In a f irst experimental series using the emptied, washed, and isolated reticuloru men of sheep, 6.3% of glucose was absorbed from an intraruminal buffer solu tion (2 L, 128 mmol/L Na+, 0.5 mmol/L glucose, 0 mmol/L galactose) within 3 0 min (P < 0.001). Reducing Na+ concentration to 10 mmol/L resulted in comp lete inhibition of glucose absorption, and the addition of 10 mmol/L galact ose (at 128 mmol/L Na+) induced a small but insignificant inhibition. In a second experimental series, the addition of 12 mmol/L glucose to an initial ly glucose-free buffer led to an increase in the transruminal potential dif ference from 34.4 to 37.1 mV within 4 min (P < 0.001). From the 12 mmol/L g lucose-containing buffer, 11.0% of glucose was absorbed within 30 min (P < 0.05). In all experiments, microbial glucose degradation in the reticulorum en was prevented by adding cefuroxime (100 mg/L) and colistin methanesulfon ate (25 mg/L) to the buffer solution. The effectiveness of antimicrobial tr eatment was verified by ex vivo incubations of buffer samples drawn from th e reticulorumen. We conclude that glucose is absorbed in a sodium-dependent manner from the reticulorumen at low and high glucose concentrations. Abso rption at high glucose concentrations is of nutritional importance because it counteracts the genesis of ruminal lactic acidosis.