Hexose transport across the basolateral membrane of the chicken jejunum.

Abstract

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 6-wk-old chickens. Uptake of hexoses was measured using a rapid filtration method. The maximal rate of transport (Vmax) for D-Glc was 2.36 nmol x mg(-1) x s(-1) and for D-Fru was 3.79 nmol x mg(-1) x s(-1). The Michaelis constants were 17.3 mmol/l for D-Glc and 40.4 mmol/l for D-Fru. D-Glc inhibited its own transport (Ki = 17.4 mmol/l) and the transport of D-Fru (Ki = 18.7 mmol/l). D-Fru inhibited its own transport (Ki = 38.1 mmol/l) and the transport of D-Glc (Ki = 40.3 mmol/l). The transport of both hexoses was Na+ independent, theophylline and cytochalasin B sensitive, and showed cis-inhibition by structural analogs. In preloaded vesicles, the uptake of D-Fru was trans-stimulated by D-Glc and 2-deoxy-D-glucose. These properties indicate the presence of a low-affinity high-capacity glucose transporter isoform (GLUT-2)-type carrier in the chicken intestine, responsible for moving both D-Glc and D-Fru across the basolateral membrane.