title: Functional involvement of rat organic anion transporter 2 (Slc22a7) in the hepatic uptake of the nonsteroidal anti-inflammatory drug ketoprofen.
abstract: Rat organic anion transporter 2 (rOat2, Slc22a7) is a sinusoidal multispecific organic anion transporter in the liver. The role of rOat2 in the hepatic uptake of drugs has not been thoroughly investigated yet. rOat2 substrates include nonsteroidal anti-inflammatory drugs, such as ketoprofen, indomethacin, and salicylate. In the present study, the uptake of ketoprofen, indomethacin, and salicylate by freshly isolated rat hepatocytes was characterized. The uptake of ketoprofen, indomethacin, and salicylate by hepatocytes was sodium-independent, and the rank order of their uptake activities was indomethacin > ketoprofen > salicylate. Kinetic analysis based on Akaike's Information Criterion suggested that the uptake of ketoprofen and indomethacin by hepatocytes consists of two saturable components and one nonsaturable one. The K(m) and V(max) values for the high- and low-affinity components for ketoprofen uptake were 0.84 and 97 microM and 35 and 1800 pmol/min/mg protein, respectively, whereas those for indomethacin were 1.1 and 140 microM and 130 and 16,000 pmol/min/mg protein, respectively. The K(m) values of the high-affinity component were similar to those for rOat2 (3.3 and 0.37 microM for ketoprofen and indomethacin, respectively). The uptake of ketoprofen by hepatocytes was significantly inhibited by probenecid and rOat2 inhibitors (indocyanine green, indomethacin, glibenclamide, and salicylate). Other inhibitors of rOatps (taurocholate and pravastatin) and rOat3 (pravastatin and p-aminohippurate) had a slight effect, but digoxin had no effect. These results suggest that rOat2 accounts partly for the hepatic uptake of ketoprofen and, presumably, indomethacin as a high-affinity site and that other transporters, such as rOatps, but not rOatp2, and rOat3, are also involved.
authors.affiliation: Graduate School of Pharmaceutical Sciences, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Morita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kusuhara
authors.forename: Yoshitane
authors.initials: Y
authors.lastname: Nozaki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endou
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005905:Glyburide / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D007208:Indocyanine Green / Q000494:pharmacology; D007660:Ketoprofen / Q000378:metabolism*; D018374:LLC-PK1 Cells; D008297:Male; D029362:Organic Anion Transporters, Sodium-Independent / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013552:Swine
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D029362:Organic Anion Transporters, Sodium-Independent; C088800:Slc22a7 protein, rat; D007660:Ketoprofen; D007208:Indocyanine Green; D011339:Probenecid; D005905:Glyburide