alpha-MeGlc and D-glucose transport by hepatopancreatic brush border membrane vesicles from prawn

Sugar transport by prawn (Penaeus japonicus) hepatopancreatic epithelium has been studied. Brush-border membrane vesicles (hBBMV) were isolated, studies of osmotic reactivity were made indicating that these vesicles were closed and with low contamination from basolateral membranes. Incubation of hBBMV in the presence of Na+ resulted in rapid sugar uptake by the vesicles with an overshoot at 5 min, achieving the equilibrium value at 60 min. The absence of Na+ or the presence of phloridzin inhibited the overshoot. This uptake appears to be dependent on the membrane potential, since K+ efflux down its concentration gradient in the presence of valinomycin accelerated sugar influx and increased the overshoot when K+-loaded hBBMV were used. The kinetic study of Na+-dependent sugar uptake reveals that values of Km and Vmax were of the same order of magnitud as those described for other absorptive epithelia