Fluoride flux in the rabbit CCD: a pH-dependent event.
We measured fluoride flux (JF; pmol.min-1.mm-1) in the isolated rabbit cortical collecting duct (CCD) to investigate the determining factors of JF. The perfusate contained 100 microM fluoride and the bath was fluoride-free. Osmotically-induced lumen-to-bath water flux did not affect JF. When perfusate pH was reduced from 7.4 to 6.1 and from 6.1 to 5.0, JF increased from 0.008 +/- 0.002 to 0.027 +/- 0.007 (P less than 0.01) and from 0.018 +/- 0.003 to 0.040 +/- 0.005 (P less than 0.01), respectively. Acetazolamide at 10(-4) M in the bath reduced JF slightly though not statistically. The anion-transport inhibitor, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS), at 10(-4) M in the perfusate did not affect JF. Substitution of luminal chloride with gluconate failed to affect JF in tubules from normal rabbits or from rabbits treated with deoxycorticosterone which stimulates chloride-bicarbonate exchange in the CCD. JF showed no correlation with transepithelial voltage which ranged from +4 to -104 mV. We conclude that the luminal pH represents the primary determining factor influencing JF in the rabbit CCD, and fluoride does not use a chloride-mediated or a DIDS-inhibitory transport pathway.
Rouch
A J
AJ
Department of Physiology and Endocrinology, School of Medicine, Medical College of Georgia, Augusta.
Whitford
G M
GM
Campbell
H T
HT
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D004594:Electrophysiology; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D005459:Fluorides / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007672:Kidney Cortex; D007685:Kidney Tubules, Collecting / Q000378:metabolism* / Q000502:physiology; D011817:Rabbits
D002712:Chlorides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D005459:Fluorides