HEXOSE-TRANSPORT ACROSS THE BASOLATERAL MEMBRANE OF THE CHICKEN JEJUNUM

The characteristics of the basolateral transport of D-glucose (D-Glc) and D-fructose (D-Fru) have been studied in membrane vesicles from the jejunum of 5- to B-wk-old chickens. Uptake of hexoses was measured us ing a rapid filtration method. The maximal rate of transport (V-max) f or D-Glc was 2.36 nmol.mg(-1).s(-1) and for D-Fru was 3.79 nmol.mg(-1) .s(-1). The Michaelis constants were 17.3 mmol/l for D-Gle and 40.4 mm ol/l for D-Fru. n-Glc inhibited its own transport (K-i = 17.4 mmol/l) and the transport of D-Fru (K-i = 18.7 mmol/l). D-Fru inhibited its ow n transport (K-i = 38.1 mmol/l) and the transport of D-Glc (K-i = 40.3 mmol/l). The transport of both hexoses was Nai independent, theophyll ine and cytochalasin B sensitive, and showed cis-inhibition by structu ral analogs. In preloaded vesicles, the uptake of D-Fru was trans-stim ulated by D-Glc and 2-deoxy-D-glucose. These properties indicate the p resence of a low-affinity high-capacity glucose transporter isoform (G LUT-2)-type carrier in the chicken intestine, responsible for moving b oth n-Glc and D-Fru across the basolateral membrane.