title: Interactions of pH and K+ conductance in cultured bovine retinal pigment epithelial cells.
abstract: Passive ion transport properties were studied in confluent monolayers of cultured bovine retinal pigment epithelial cells using intracellular microelectrode technique. The mean stable intracellular (designated by subscript i) potential was -59.1 +/- 0.8 (SE) mV. Extracellular (designated by subscript o) acidification induced a depolarization, whereas alkalinization induced a hyperpolarization. These effects were observed both in bicarbonate-free as well as in HCO3- Ringer (pHo changed by varying [HCO3-]o at constant pCO2). Acidification of pHi (changed by addition and removal of butyrate, CO2 or NH3) also caused a depolarization. Complete removal of HCO3-/CO2 at constant pHo caused a hyperpolarization. K+ transference, checked by applying high K+o, increased with K+o. It decreased with both extra and intracellular acidification and increased with alkalinization. In the presence of Ba2+, voltage reactions to changes in either pHo or pHi were greatly reduced. Depolarization by 40 mM K+ caused a similar reduction. It is suggested that K+ conductance of bovine retinal pigment epithelial cells is reduced by either intra- or extracellular acidification at normal [K+]o. Depolarization by high K+ induces an increase in K+ transference and reduces pH sensitivity.
mesh_terms: D000200:Action Potentials; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000378:metabolism; D001639:Bicarbonates / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D008433:Mathematics; D010857:Pigment Epithelium of Eye / Q000166:cytology*; D011188:Potassium / Q000502:physiology*
chemical_list: D001639:Bicarbonates; D000643:Ammonium Chloride; D001464:Barium; D011188:Potassium