The sodium electrochemical potential-mediated uphill transport of D-glucose in renal brush border membrane vesicles

The uphill transport of D-glucose in renal brush border membrane vesicles was correlated with the Na+ electrochemical gradient. Each component of the electrochemical potential, the membrane potential (outside positive) or the Na+ chemical gradient, when assayed independently, supported the concentrative uptake of the sugar. When the two components were combined, the rates of D-glucose uptake were additive. Accumulation of D-glucose as a function of various Na+ gradients, in the absence of a membrane potential, suggests a 1:1 stoichiometry between sugar and Na+ uptake. These findings are consistent with the role of ionic gradients in energizing uphill solute transport.