title: Ionic conductances of cultured principal cell epithelium of renal collecting duct.
abstract: The ionic conductive properties were studied of epithelia of collecting duct principal cells which had been grown in primary tissue culture from renal cortex/capsule explants. When pretreated with aldosterone (10(-6) mol/l) and bathed on either surface with isotonic HCO3(-)-free Ringer's solution, the transepithelial voltage, Vte, varied between -21 and -72 mV (apical surface negative) while the transepithelial resistance, Rte, ranged from 0.4 to 1.5 k omega cm2. By 10:1 step-changes in Na+ concentration the apical cell membrane was shown to have a high conductivity for sodium, inhibitable by amiloride, 10(-6) mol/l. However, contrary to observations in natural collecting duct under control conditions, amiloride never reversed the polarity of Vte even at 10(-4) mol/l. Both the apical and the basolateral cell membranes were conductive for potassium and both conductivities were inhibitable by Ba2+ (5 mmol/l). 10:1 reduction of apical Cl- concentration strongly hyperpolarized Vte with a monophasic time course suggesting the presence of a paracellular shunt conductance for Cl-. In addition there may be a small Cl- conductance present in the apical cell membrane since apical application of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPAB) at 10(-7) mol/l produced a minute but significant hyperpolarization. On the other hand, 10:1 reduction of basolateral Cl- concentration caused a biphasic change in Vte (initial depolarization, followed by repolarization) which indicates the presence of a large Cl- conductance in the basolateral cell membrane. The latter was not inhibitable by 10(-7) mol/l NPPAB. Higher concentrations of this and of an other Cl-channel blocker produced non-specific effects.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Medizinische Universitätsklinik, Sektion Nephrologie, Heidelberg, Federal Republic of Germany.
authors.forename: P
authors.initials: P
authors.lastname: Gross
authors.forename: W W
authors.initials: WW
authors.lastname: Minuth
authors.forename: M
authors.initials: M
authors.lastname: Ketteler
authors.forename: E
authors.initials: E
authors.lastname: Frömter
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002712:Chlorides / Q000378:metabolism*; D046508:Culture Techniques; D004847:Epithelial Cells; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D011817:Rabbits; D015222:Sodium Channels / Q000378:metabolism*
chemical_list: D002712:Chlorides; D015222:Sodium Channels