title: p-Aminohippurate transport at the apical membrane in the OK kidney epithelial cell line.
abstract: OBJECTIVE
  We investigated the characteristics of transport of an organic anion, p-aminohippurate (PAH), at the apical membrane in a kidney epithelial cell line OK.
  
  
  METHODS
  Efflux and uptake of [14C]PAH across the apical membrane were measured using OK cell monolayers grown on microporous membrane filters.
  
  
  RESULTS
  PAH efflux to the apical side was greater than that to the basolateral side and significantly inhibited by probenecid. Diethyl pyrocarbonate (DEPC), an inhibitor of potential-sensitive organic anion transport, significantly decreased PAH efflux to the apical side. Moreover, PAH efflux to the apical side was significantly decreased on incubation with high potassium buffer, as compared with control condition. Extracellular pH and Cl- had no effect on PAH efflux across the apical membrane. PAH uptake from the apical side was inhibited by various organic anions, and the inhibition patterns of PAH uptake from the apical and basolateral sides by various dicarboxylates were similar.
  
  
  CONCLUSIONS
  These results suggested that PAH efflux to the apical side in OK cells was mediated by a potential-sensitive transport system, but not by an anion exchanger. Moreover, PAH uptake from the apical side was mediated by a specific transport system, which interacts with various organic anions and dicarboxylates.
authors.affiliation: Department of Pharmacy, Kyoto University Hospital, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Habu
authors.forename: Ikuko
authors.initials: I
authors.lastname: Yano
authors.forename: Yukiya
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saito
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Inui
mesh_terms: D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002712:Chlorides / Q000493:pharmacokinetics; D004847:Epithelial Cells / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D009893:Opossums; D011339:Probenecid / Q000493:pharmacokinetics; D010130:p-Aminohippuric Acid / Q000493:pharmacokinetics*
chemical_list: D002712:Chlorides; D011339:Probenecid; D010130:p-Aminohippuric Acid