Sulfate and oxalate exchange for bicarbonate across the basolateral membrane of rabbit ileum.
The purpose of these studies was to further define the transport of SO4(2-) and oxalate across the basolateral membrane (BLM) of rabbit ileum. We previously found evidence for Cl-(-)SO4(2-) exchange but no evidence for carrier-mediated oxalate transport. A HCO3- gradient (but not a pH gradient) was found to stimulate SO4(2-) and oxalate uptake in BLM vesicles; uptake was inhibited by DIDS. Oxalate cis-inhibited HCO3- gradient SO4(2-) uptake and trans-stimulated SO4(2-) uptake, suggesting SO4(2-) and oxalate used the same carrier (SO4(2-)- and oxalate-HCO3-exchange). Cl- had no effect on HCO3- gradient-stimulated SO4(2-) uptake, indicating that Cl(-)-SO4(2-) exchange was a different carrier. Other substrates found to be transported on the HCO3- exchanger were oxaloacetate and S2O3(2-)-.SO4(2-), S2O3(2-). and oxalate were found to also use the SO4(2-)-Cl- exchanger, whereas oxalate was only transported on the HCO3- exchanger. SO4(2-)-HCO3- exchange was found on villus, but not crypt cell, BLM. These results indicate that there is a SO4(2-)-HCO3- exchanger on the BLM of villus cells that also transports oxalate, and along with our previous studies, the results provide evidence for the transepithelial transport of oxalate.
Knickelbein
R G
RG
Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
Dobbins
J W
JW
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism* / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology; D007082:Ileum / Q000502:physiology*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D009130:Muscle, Smooth / Q000502:physiology; D010070:Oxalates / Q000378:metabolism* / Q000494:pharmacology; D011817:Rabbits; D013431:Sulfates / Q000378:metabolism*
D001639:Bicarbonates; D002712:Chlorides; D010070:Oxalates; D013431:Sulfates