Na+ and K+ fluxes stimulated by Na+-coupled glucose transport: Evidence for a Ba2+-insensitive K+ efflux pathway in rabbit proximal tubules

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Abstract
Addition of glucose or the nonmetabolizable analogue α-methyl-d-glucoside to rabbit proximal tubules suspended in a glucoseand alanine-free buffer caused a sustained increase in intracellular Na+ content (+43±7 nmol · (mg protein)−1) and a concomitant but larger decrease in K+ content (−72±11 nmol· (mg protein)−1). A component of the net K+ efflux was Ba2+ insensitive, and was inhibited by high (1mm) but not low (10 μm) concentrations of the diuretics, furosemide and bumetanide. The increase in intracellular Na+ content is consistent with the view that the increased rates of Na+ and water transport seen in the proximal tubule in the presence of glucose can be attributed (at least in part) to a stimulation of basolateral pump activity by an increased [Na+] i .