title: The paracellular permeability of opossum kidney cells, a proximal tubule cell line.
abstract: The paracellular permeability of opossum kidney cells, a proximal tubule cell line.
  
  
  BACKGROUND
  The regulation of the unusually leaky paracellular pathway of the proximal tubule is poorly understood partially because of the lack of an appropriate in vitro cell model. In this study, we determined whether the paracellular permeability of opossum kidney (OK) cells would resemble that of the in vivo proximal tubule epithelium.
  
  
  METHODS
  The parental and subclonal OK cells and, for comparison, LLC-PK1 cells were cultured on permeable Transwell supports. The apparent paracellular permeability coefficient (Papp) for the extracellular marker 3H-mannitol was determined.
  
  
  RESULTS
  The Papp of OK cell sheets (12.17 x10-6 cm/sec) was remarkably close to the previously reported Papp of rat proximal tubules. The Papp of LLC-PK1 cells, another proximal tubule cell line, however, was approximately 20-fold lower than that of both OK cells and the in vivo proximal tubule. Phorbol 12-myristate 13-acetate, a protein kinase C activator, enhanced the Papp of OK cell sheets. The characteristic response of paracellular permeability to Ca2+ switch was demonstrated in OK cell sheets. Slight variations of Papp among several OK subclones were observed. Basal to apical Papp was uniformly higher than apical to basal Papp, independent of cell subtype. This rectification was attenuated by inhibition of active transport.
  
  
  CONCLUSIONS
  OK cell sheets cultured on Transwell supports possess a leaky paracellular pathway resembling that of the proximal tubule epithelium in vivo.
authors.affiliation: Department of Medicine and Physiology and Biophysics, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
authors.forename: M
authors.initials: M
authors.lastname: Liang
authors.forename: C R
authors.initials: CR
authors.lastname: Ramsey
authors.forename: F G
authors.initials: FG
authors.lastname: Knox
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002118:Calcium / Q000493:pharmacokinetics; D002273:Carcinogens / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002999:Clone Cells; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism*; D018374:LLC-PK1 Cells / Q000378:metabolism; D008353:Mannitol / Q000493:pharmacokinetics; D009399:Nephrons / Q000166:cytology / Q000378:metabolism; D009893:Opossums; D012964:Sodium / Q000493:pharmacokinetics; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019108:Tight Junctions / Q000378:metabolism; D014316:Tritium; D019459:Urothelium / Q000166:cytology / Q000378:metabolism
chemical_list: D000889:Anti-Arrhythmia Agents; D002273:Carcinogens; D014316:Tritium; D008353:Mannitol; D000584:Amiloride; D012964:Sodium; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C039614:ethylisopropylamiloride