Sulphate-ion/sodium-ion co-transport by brush-border membrane vesicles isolated from rat kidney cortex.
Uptake of SO(4) (2-) into brush-border membrane vesicles isolated from rat kindey cortex by a Ca(2+)-precipitation method was investigated by using a rapid-filtration technique. Uptake of SO(4) (2-) by the vesicles was osmotically sensitive and represented transport into an intra-vesicular space. Transport of SO(4) (2-) by brush-border membranes was stimulated in the presence of Na(+), compared with the presence of K(+) or other univalent cations. A typical ;overshoot' phenomenon was observed in the presence of an NaCl gradient (100mm-Na(+) outside/zero mm-Na(+) inside). Radioactive-SO(4) (2-) exchange was faster in the presence of Na(+) than in the presence of K(+). Addition of gramicidin-D, an ionophore for univalent cations, decreased the Na(+)-gradient-driven SO(4) (2-) uptake. SO(4) (2-) uptake was only saturable in the presence of Na(+). Counter-transport of Na(+)-dependent SO(4) (2-) transport was shown with MoO(4) (2-) and S(2)O(3) (2-), but not with PO(4) (2-). Changing the electrical potential difference across the vesicle membrane by establishing different diffusion potentials (anion replacement; K(+) gradient+/-valinomycin) was not able to alter Na(+)-dependent SO(4) (2-) uptake. The experiments indicate the presence of an electroneutral Na(+)/SO(4) (2-)-co-transport system in brush-border membrane vesicles isolated from rat kidney cortex.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002412:Cations / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D006096:Gramicidin / Q000494:pharmacology; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D008628:Mercury / Q000494:pharmacology; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D009550:Nigericin / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D014634:Valinomycin / Q000494:pharmacology
D002412:Cations; D013431:Sulfates; D006096:Gramicidin; D014634:Valinomycin; D012964:Sodium; D008628:Mercury; D009550:Nigericin