title: Electrical properties of cultured renal tubular cells (OK) grown in confluent monolayers.
abstract: OK cells grown to confluent monolayers were investigated by microelectrode techniques and microinjection. Cell membrane potential difference (PDm) in bicarbonate-free solution is -61.8 +/- 0.6 mV (n = 208), cell membrane resistance (Rm) amounts to 1.4 +/- 0.2 k omega. cm2 (n = 8). The apparent transference number for potassium (t'k+) is 71 +/- 3% (n = 28) and can be reduced by 3 mmol/l BaCl2 to 7.5 +/- 4.0%; (n = 8). In the presence of extracellular CO2 and HCO3- (pH 7.4) the cells acidify by 0.34 +/- 0.05 pH units (n = 12). This leads to a depolarization of PDm by 8.4 +/- 1.8 mV (n = 8), an increase in Rm by 49 +/- 10% (n = 10), and a reduction of K+-conductance to 63 +/- 5% (n = 13). Intracellular acidification by the NH4Cl-prepulse technique also inhibits K+-conductance and depolarizes the membrane. Recovery from an intracellular acid load is reflected by cell membrane repolarization. This recovery can be inhibited by amiloride (10(-3) mol/l). Na+- and Cl- -conductances could not be detected. The transepithelial resistance (Rte) of OK cell monolayers 1 day after plating is 41 +/- 6 omega.cm2 and decreases with time after plating. Intercellular communication (electrical or dye coupling) was not observed.
  
  
  CONCLUSIONS
  1. The membrane potential of OK cells is largely determined by a pH-sensitive, barium-blockable K+-conductance. 2. Amiloride-blockable Na+/H+-exchange is reflected by membrane potential changes via this K+-conductance. 3. Monolayers of OK cells are electrically leaky.
authors.affiliation: Physiologisches Institut, Universität Würzburg, Federal Republic of Germany.
authors.forename: J S
authors.initials: JS
authors.lastname: Schwegler
authors.forename: A
authors.initials: A
authors.lastname: Heuner
authors.forename: S
authors.initials: S
authors.lastname: Silbernagl
mesh_terms: D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D004553:Electric Conductivity; D004848:Epithelium / Q000502:physiology; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D007546:Isoquinolines; D007684:Kidney Tubules / Q000502:physiology*; D008564:Membrane Potentials; D008845:Microinjections; D008856:Microscopy, Fluorescence; D009893:Opossums; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D002712:Chlorides; D005456:Fluorescent Dyes; D007546:Isoquinolines; D001464:Barium; D000584:Amiloride; C017475:lucifer yellow; D012964:Sodium; D011188:Potassium