Influence of food deprivation on the transport of 3-O-methyl-α- d -glucose across the isolated ruminal epithelium of sheep

摘要: Recent studies provided evidence that the ruminal epithelium is able to absorb D-glucose even at physiologically low intraruminal concentrations. To elucidate whether transport shows adaptive responses during food deprivation, of 3-0-methyl-alpha-D-glucose (3-OMG), a hardly metabolizable analogue, was measured in isolated epithelia obtained from hay-fed or food-deprived adult sheep. In both groups, significant net absorption 3-OMG serosal side (in vivo: blood oriented) could be detected concentrations between 0.25 mM and 5 mM. Net abolished by mucosal lumen addition phlorizin, an inhibitor sodium glucose-linked transporter 1 (SGLT-1). followed Michaelis-Menten kinetics, but apparent affinity maximal capacity were lower contrast decrease (secondary) active transport, serosal-to-mucosal permeation increased after suggesting elevated passive transfer. It concluded altered characteristics are either part global energy-sparing process deprivation (i.e., lowered activity Na+/K+-ATPase) result specific down-regulation SGLT-1.