Similarity in effects of Na+ gradients and membrane potentials ond-glucose transport by, and phlorizin binding to, vesicles derived from brush borders of rabbit intestinal mucosal cells

Both the presence of sodium and of an electrical potential difference across the membrane have been found to be necessary in order to achieve optimald-glucose-protectable phlorizin binding to brush border membranes from rabbit small intestine. The effect of $\Delta \tilde \mu _{Na} $ on phlorizin binding shows a close similarity to that ond-glucose transport, confirming that phlorizin is indeed bound to thed-glucose transporting protein. Possible modulations of binding by a transmembrane potential are discussed on the basis of some models.