title: Characterization of the carrier-mediated transport of ketoprofen, a nonsteroidal anti-inflammatory drug, in rabbit corneal epithelium cells.
abstract: OBJECTIVE
  Using rabbit corneal epithelial cells (RCECs), the transport of a nonsteroidal anti-inflammatory drug (NSAID) [(3)H]ketoprofen across the cornea was investigated with the aim of revealing the mechanism of uptake.
  
  
  METHODS
  [(3)H]Ketoprofen transport was evaluated by measuring the permeability across the RCECs layers.
  
  
  RESULTS
  [(3)H]Ketoprofen uptake was time, temperature and pH dependent. Maximal uptake occurred from a solution with a pH of 5.25. Uptake was also reduced by metabolic inhibitors (sodium azide and dinitrophenol (DNP)) and proton-linked monocarboxylate transporter (MCT) inhibitors (carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) and α-cyano-4-hydroxycinnamic acid (CHC)). [(3)H]Ketoprofen uptake was significantly inhibited by various monocarboxylates and other NSAIDs and by MCT and/or organic anion transporter (OAT) inhibitors probenecid and p-aminohippurate, but was unaffected by organic anion-transporting polypeptide (OATP) inhibitors bromosulfophthalein and taurocholate. The specific uptake of [(3)H]ketoprofen was saturable. Eadie-Hofstee plots indicated the involvement of high- and low-affinity components. The K(m) and V(max) values for the high- and low-affinity components of [(3)H]ketoprofen uptake were 0.56 and 24 mm, and 0.37 and 61 nmol/min/mg of protein, respectively. Benzoic acid, a substrate and inhibitor of MCTs, selectively inhibited low-affinity [(3)H]ketoprofen uptake. Conversely, indometacin inhibited high-affinity [(3)H]ketoprofen uptake.
  
  
  CONCLUSIONS
  The results of this study suggest that the monocarboxylate transport system partly accounts for the low-affinity component of [(3)H]ketoprofen uptake, and that the carrier-mediated transport systems such as the OAT family, shared by NSAIDs account for the high-affinity component.
authors.affiliation: Nara Research and Development Center, Santen Pharmaceutical Co., Ltd, Ikoma-shi, Nara.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Fujii
authors.forename: Hideki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Itoh
authors.forename: Shizuo
authors.initials: S
authors.lastname: Yamada
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Deguchi
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kawazu
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics*; D001692:Biological Transport; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007660:Ketoprofen / Q000493:pharmacokinetics*; D008297:Male; D026901:Membrane Transport Proteins / Q000378:metabolism; D011817:Rabbits; D013696:Temperature
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D026901:Membrane Transport Proteins; D007660:Ketoprofen