Publications

• Oxalate transport via the sulfate/HCO3 exchanger in rabbit renal basolateral membrane vesicles.

  Kuo S.M., Aronson P.S.

  We evaluated the mechanism of oxalate transport in basolateral membrane vesicles isolated from the rabbit renal cortex. An outward HCO3-gradient induced the transient uphill accumulation of oxalate and sulfate, indicating the presence of oxalate/HCO3- exchange and sulfate/HCO3-exchange. For oxalat ... >> More

  We evaluated the mechanism of oxalate transport in basolateral membrane vesicles isolated from the rabbit renal cortex. An outward HCO3-gradient induced the transient uphill accumulation of oxalate and sulfate, indicating the presence of oxalate/HCO3- exchange and sulfate/HCO3-exchange. For oxalate, sulfate, or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, the K1/2 value for oxalate/HCO3-exchange was nearly identical to that for sulfate/HCO3-exchange, suggesting that both exchange processes occur via the same transport system. This was further supported by the finding of sulfate/oxalate exchange. Thiosulfate/sulfate exchange and thiosulfate/oxalate exchange were also demonstrated, but a variety of other tested anions including Cl-, p-aminohippurate, and lactate did not exchange for sulfate or oxalate. Na+ did not affect sulfate or oxalate transport, indicating that neither anion undergoes Na+ co-transport or Na+-dependent anion exchange in these membrane vesicles. Finally, we found that the stoichiometry of exchange is 1 sulfate or oxalate per 2 HCO3-, or a thermodynamically equivalent process. We conclude that oxalate, but not other organic or inorganic anions of physiologic importance, can share the sulfate/HCO3-exchanger in renal basolateral membrane vesicles. In series with luminal membrane oxalate/Cl- (formate) exchange, exchange of oxalate for HCO3- or sulfate across the basolateral membrane provides a possible transcellular route for oxalate transport in the proximal tubule. << Less

  J Biol Chem 263:9710-9717(1988) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Ability of sat-1 to transport sulfate, bicarbonate, or oxalate under physiological conditions.

  Krick W., Schnedler N., Burckhardt G., Burckhardt B.C.

  Tubular reabsorption of sulfate is achieved by the sodium-dependent sulfate transporter, NaSi-1, located at the apical membrane, and the sulfate-anion exchanger, sat-1, located at the basolateral membrane. To delineate the physiological role of rat sat-1, [(35)S]sulfate and [(14)C]oxalate uptake i ... >> More

  Tubular reabsorption of sulfate is achieved by the sodium-dependent sulfate transporter, NaSi-1, located at the apical membrane, and the sulfate-anion exchanger, sat-1, located at the basolateral membrane. To delineate the physiological role of rat sat-1, [(35)S]sulfate and [(14)C]oxalate uptake into sat-1-expressing oocytes was determined under various experimental conditions. Influx of [(35)S]sulfate was inhibited by bicarbonate, thiosulfate, sulfite, and oxalate, but not by sulfamate and sulfide, in a competitive manner with K(i) values of 2.7 +/- 1.3 mM, 101.7 +/- 9.7 microM, 53.8 +/-10.9 microM, and 63.5 +/-38.7 microM, respectively. Vice versa, [(14)C]oxalate uptake was inhibited by sulfate with a K(i) of 85.9 +/-9.5 microM. The competitive type of inhibition indicates that these compounds are most likely substrates of sat-1. Physiological plasma bicarbonate concentrations (25 mM) reduced sulfate and oxalate uptake by more than 75%. Simultaneous application of sulfate, bicarbonate, and oxalate abolished sulfate as well as oxalate uptake. These data and electrophysiological studies using a two-electrode voltage-clamp device provide evidence that sat-1 preferentially works as an electroneutral sulfate-bicarbonate or oxalate-bicarbonate exchanger. In kidney proximal tubule cells, sat-1 likely completes sulfate reabsorption from the ultrafiltrate across the basolateral membrane in exchange for bicarbonate. In hepatocytes, oxalate extrusion is most probably mediated either by an exchange for sulfate or bicarbonate. << Less

  Am. J. Physiol. 297:F145-F154(2009) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.