查看文章

Recent evidence suggests that apical membrane Cl⁻-oxalate exchange plays a major role in mediating Cl⁻ absorption in the renal proximal tubule. To sustain steady-state Cl⁻ absorption by a mechanism of exchange for intracellular oxalate requires the presence of one or more pathways for recycling oxalate from lumen to cell. Accordingly, we evaluated the mechanisms of oxalate transport in luminal membrane vesicles isolated from the rabbit renal cortex. We found that transport of oxalate by Na⁺ cotransport is negligible compared to the transport of sulfate. In contrast, we demonstrated that oxalate shares the electroneutral pathway mediating Na⁺-independent sulfate-carbonate exchange. We also demonstrated the presence of OH⁻-oxalate exchange (indistinguishable from H⁺-oxalate cotransport). The process of OH⁻-oxalate exchange was electrogenic and partially inhibited by Cl⁻, indicating that it occurs, at …