Oxalate transport via the sulfate/HCO3 exchanger in rabbit renal basolateral membrane vesicles.
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.
Kuo
S M
SM
Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
Aronson
P S
PS
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D027321:Anion Transport Proteins; D017920:Antiporters; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D007672:Kidney Cortex / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D010070:Oxalates / Q000378:metabolism*; D019815:Oxalic Acid; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D000076988:Sulfate Transporters; D013431:Sulfates / Q000378:metabolism; D014634:Valinomycin / Q000494:pharmacology
D027321:Anion Transport Proteins; D017920:Antiporters; D001639:Bicarbonates; D002352:Carrier Proteins; D002712:Chlorides; D007773:Lactates; D010070:Oxalates; C056459:Slc26a1 protein, rat; D000076988:Sulfate Transporters; D013431:Sulfates; D014634:Valinomycin; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D019344:Lactic Acid; D019815:Oxalic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium