Volume regulatory Cl- loss after Na+ pump inhibition in CCT principal cells.
Ouabain caused rabbit cortical collecting tubule (CCT) principal cells to swell 53% and then undergo regulatory volume decrease (RVD) at a rate of 4%/min to a new steady-state volume 10% below control. Reduction of peritubular Cl- concentration transiently depolarized transepithelial potential (Vte) by 36 mV and stimulated the rate of RVD 30-fold. Peritubular application of 0.5 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited RVD 74%. In contrast, luminal Cl- reduction or application of DIDS had no effect on RVD. A 10-fold elevation of perfusate K+ caused volume-regulated cells to swell 23% at a rate of 60%/min. Removal of luminal Cl- had no effect on either the rate or magnitude of K+ swelling. Peritubular or bilateral Cl- removal, however, inhibited the rate of K+ swelling by 96 and 99%, respectively. Substitution of bath Cl- for Br-, SCN-, or I- inhibited the rate of K+ swelling by 40, 38, and 98%, respectively. Surprisingly, NO3- inhibited the rate of K+ swelling by 82%. All Cl- substitutes tested transiently depolarized Vte by 3-49 mV. These results suggest strongly that RVD is mediated by a basolateral Cl- channel with a high selectivity for Cl- over other anions.
Strange
K
K
Children's Hospital, Division of Nephrology, Harvard Medical School, Boston, Massachusetts 02115.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D001693:Biological Transport, Active; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D004594:Electrophysiology; D004848:Epithelium / Q000502:physiology; D007672:Kidney Cortex; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D009994:Osmolar Concentration; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*
D000838:Anions; D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium