title: Glucose is absorbed in a sodium-dependent manner from forestomach contents of sheep.
abstract: Intraruminal glucose is thought to be completely converted to short-chain fatty acids (SCFA) by symbiotic microorganisms. Nevertheless, earlier in vitro studies evidenced the expression of the sodium glucose-linked transporter (SGLT)-1, in the ovine ruminal epithelium. The present study aimed to determine whether the ruminal SGLT-1 is functionally important in vivo. In a first experimental series using the emptied, washed, and isolated reticulorumen of sheep, 6.3% of glucose was absorbed from an intraruminal buffer solution (2 L, 128 mmol/L Na(+), 0.5 mmol/L glucose, 0 mmol/L galactose) within 30 min (P < 0.001). Reducing Na(+) concentration to 10 mmol/L resulted in complete inhibition of glucose absorption, and the addition of 10 mmol/L galactose (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 initially glucose-free buffer led to an increase in the transruminal potential difference from 34.4 to 37.1 mV within 4 min (P < 0.001). From the 12 mmol/L glucose-containing buffer, 11.0% of glucose was absorbed within 30 min (P < 0.05). In all experiments, microbial glucose degradation in the reticulorumen was prevented by adding cefuroxime (100 mg/L) and colistin methanesulfonate (25 mg/L) to the buffer solution. The effectiveness of antimicrobial treatment was verified by ex vivo incubations of buffer samples drawn from the reticulorumen. We conclude that glucose is absorbed in a sodium-dependent manner from the reticulorumen at low and high glucose concentrations. Absorption at high glucose concentrations is of nutritional importance because it counteracts the genesis of ruminal lactic acidosis.
authors.affiliation: Department of Veterinary Physiology, Leipzig University, D-04103 Leipzig, Germany.
authors.forename: J R
authors.initials: JR
authors.lastname: Aschenbach
authors.forename: S K
authors.initials: SK
authors.lastname: Bhatia
authors.forename: H
authors.initials: H
authors.lastname: Pfannkuche
authors.forename: G
authors.initials: G
authors.lastname: Gäbel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002444:Cefuroxime / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D005260:Female; D005690:Galactose / Q000494:pharmacology; D005947:Glucose / Q000493:pharmacokinetics*; D007408:Intestinal Absorption / Q000187:drug effects; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000502:physiology*; D012417:Rumen / Q000187:drug effects / Q000378:metabolism*; D012756:Sheep; D012964:Sodium / Q000494:pharmacology
chemical_list: D002511:Cephalosporins; D009004:Monosaccharide Transport Proteins; D012964:Sodium; D005947:Glucose; D002444:Cefuroxime; D005690:Galactose