Transport characteristics of the apical anion exchanger of rabbit cortical collecting duct beta-cells.
To functionally characterize transport properties of the apical anion exchanger of rabbit beta-intercalated cells, the mean change in anion exchange activity, dpHi/dt (where pHi is intracellular pH), was measured in response to lumen Cl- replacement with gluconate in perfused cortical collecting ducts (CCDs). beta-Cell apical anion exchange was not affected by 15-min exposure to 0.2 mM lumen DIDS in the presence of 115 mM Cl-. In contrast, apical anion exchange was significantly inhibited by 0.1 mM lumen DIDS in the absence of Cl-. beta-Cell apical anion exchange was unchanged by 15 mM maleic anhydride, 10 mM phenylglyoxal, 0.2 mM niflumic acid, 1 mM edecrin, 1 mM furosemide, 1 mM probenecid, or 0.1 mM diphenylamine-2-carboxylate. However, beta-cell apical anion exchange was inhibited by alpha-cyano-4-hydroxycinnamic acid, with an IC50 of 2.4 mM. Substitution of either sulfate or gluconate for lumen Cl- resulted in a similar rate of alkalinization. Conversely, pHi was unchanged by substitution of sulfate for lumen gluconate, confirming the lack of transport of sulfate on the beta-cell apical anion exchanger. Taken together, the results demonstrate a distinct "fingerprint" of the rabbit CCD beta-cell apical anion exchanger that is unlike that of other known anion exchangers.
Emmons
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Departments of Internal Medicine, University of Cincinnati and Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio 45267-0585, USA.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D017920:Antiporters / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000494:pharmacology; D005942:Gluconates / Q000494:pharmacology; D066298:In Vitro Techniques; D007672:Kidney Cortex; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011817:Rabbits; D013267:Stilbenes / Q000494:pharmacology; D013431:Sulfates / Q000378:metabolism
D017920:Antiporters; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D005942:Gluconates; D013267:Stilbenes; D013431:Sulfates; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; C030691:gluconic acid