title: Effect of changes in extracellular potassium on intracellular pH in principal cells of frog skin.
abstract: Intracellular pH (pHi), apical membrane potential (Va), and fractional apical membrane resistance (FRa) were measured in principal cells of isolated frog skin (Rana pipiens) with double-barreled microelectrodes under short-circuit and open-circuit conditions. Basolateral exposure to high K+ concentration or Ba2+ depolarized V(a), decreased short-circuit current, and increased FRa and pHi. However, an increase in K+ subsequent to Ba2+ application did not induce additional changes in these parameters. High basolateral K+, previously shown to increase apical K+ secretion (N. S. Bricker, T. Biber, and H. H. Ussing. J. Clin. Invest. 41: 88-99, 1963), also increased apical Na+ conductance. The depolarization and intracellular alkalinization induced by high K+ were also observed in absence of Na+, Cl-, and HCO3- and in presence of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Under all these conditions pHi moved toward electrochemical equilibrium. Reduced basolateral K+ hyperpolarized V(a) and decreased pHi. The data suggest that depolarization and hyperpolarization of the apical and/or basolateral membrane are associated with an increase and decrease, respectively, in pHi without involvement of Na(+)-H+, Cl(-)-HCO3-, or K(+)-H+ exchange and are apparently also independent of an active H+ secretion pathway. This indicates the presence of a potential-dependent H+ and/or OH- conductance in the apical and/or basolateral cell membrane that may play an important role in pHi regulation and signal transduction.
authors.affiliation: Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551.
authors.forename: V
authors.initials: V
authors.lastname: Lyall
authors.forename: T S
authors.initials: TS
authors.lastname: Belcher
authors.forename: T U
authors.initials: TU
authors.lastname: Biber
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004563:Electrochemistry; D005110:Extracellular Space / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism*; D007474:Ion Exchange; D011188:Potassium / Q000378:metabolism*; D011894:Rana pipiens; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D001464:Barium; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium