Glucose uptake into plasma membrane vesicles from the maternal surface of human placenta

Glucose uptake into plasma membrane vesicles from the maternal surface of the human placenta was measured with the Millipore filtration technique. Uptake off D-glucose was dependent on the osmolarity of the incubation medium surrounding the vesicles. Uptake of D-glucose exceeded that of L-glucose. The uptake of D-glucose was not enhanced by placing 100 mM NaCl or NaSCN in the medium outside the vesicles (none inside) at the onset of uptake determinations. D-glucose transport was inhibited by cytochalasin B; phloretin, phlorizin, and 1-fluoro-2,4-dinitrobenzene. D-glucose uptake was inhibited by 2-deoxy-D-glucose, 3-O-methyl-D-glucose and to a lesser extent by D-galactose. It was not inhibited by alpha-methyl-D-glucoside. Cytochalasin B binding to the vesicles was 30% inhibited in the presence of 80 mM D-glucose. The results indicate that the system for facilitated transport of D-glucose at the maternal face of the placenta is distinctly different from that on the brush-border membrane of intestine or renal tubule and more closely resembles that of human erythrocyte.