HEXOSE-TRANSPORT ACROSS THE APICAL AND BASOLATERAL MEMBRANE OF ENTEROCYTES FROM DIFFERENT REGIONS OF THE CHICKEN INTESTINE

The properties of hexose transport across the apical and basolateral m embranes of chicken enterocytes have been studied in the small and lar ge intestine. Results show that(a) isolated epithelial cells from all segments except the coprodeum can accumulate 3-O-methylglucose (Glc3Me ) against a concentration gradi ent, by a Na+-dependent and phloridzin -sensitive mechanism. (b) The cell cumulative capacity for Glc3Me (con trol/phloridzin-incubated cells) is lower in the small intestine than in the large intestine (rectum = proximal caecum = ileum > jejunum > d uodenum). (c) Theophylline enhances the cell Glc3Me cumulative capacit y 2.9-fold in the duodenum and 2.4-fold in the jejunum but has no effe ct in the other segments studied. (d) Analysis of sugar uptake indicat es that net hexose influx rates decrease from proximal to distal regio ns: jejunum > duodenum > ileum = proximal caecum = rectum for the apic al transport system (cc-methyl glucoside as substrate and phloridzin a s inhibitor) and duodenum > jejunum > ileum = proximal caecum = rectum for the basolateral system (2-deoxyglucose; theophylline). (e) The du odenum and the jejunum show high apical and basolateral hexose transpo rt rates, which confer a significant capacity for sugar absorption on the proximal intestine. More distal regions, including the ileum, the proximal caecum and the rectum, have transport systems analogous to th ose of the proximal intestine that keep a considerable potential capab ility to recover hexoses from the lumen.