Functional characterization of alpha- and beta-intercalated cell types in rabbit cortical collecting duct.
Single-cell electrical measurements and spectrophotometric determinations of intracellular pH were used to determine unique features of alpha- and beta-intercalated cells (alpha-IC, beta-IC) in in vitro perfused rabbit cortical collecting ducts (CCD). pHi rose in alpha-IC and fell in beta-IC after bath Cl- removal. Luminal Cl- removal did not change pHi of alpha-IC, but pHi of beta-IC rose by 0.36 +/- 0.01 pH units. Cl- concentration-dependent recovery of beta-IC pHi revealed a Cl- Km of 18.7 mM for the luminal Cl(-) -HCO3- exchanger. Measurements of basolateral membrane voltage (Vbl) also showed two IC cell types. Removal of luminal Cl- did not change Vbl in alpha-IC, whereas Vbl hyperpolarized by a mean of 73.2 +/- 3.5 mV in beta-IC. Reducing bath Cl- depolarized both alpha- and beta-IC Vbl. In alpha-IC a large repolarization of 39.8 +/- 5.2 mV followed acute depolarization after bath Cl- removal. Reducing bath HCO3- (constant CO2) had little effect on beta-IC Vbl, whereas alpha-IC Vbl depolarized by 5.2 +/- 0.7 mV. Reducing luminal HCO3- in the absence of luminal Cl- produced a 17.6 +/- 1.8 mV depolarization in beta-IC. This change was independent of luminal Na+ and was not blocked by luminal 10(-4) M 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). In beta-IC, Vbl was not altered by either bath or lumen DIDS in the presence of luminal Cl-. However, when luminal Cl- was removed, luminal DIDS reversibly depolarized Vbl by 9.6 +/- 2.9 mV.(ABSTRACT TRUNCATED AT 250 WORDS)
Furuya
H
H
Department of Medicine, Vanderbilt University, Nashville, Tennessee.
Breyer
M D
MD
Jacobson
H R
HR
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides / Q000378:metabolism; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000502:physiology; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000166:cytology / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D010477:Perfusion; D011817:Rabbits
D002352:Carrier Proteins; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D005033:Ethylmaleimide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid