title: A Transporter of Ibuprofen is Upregulated in MDCK I Cells under Hyperosmotic Culture Conditions.
abstract: Ibuprofen is a widely used drug. It has been identified as an inhibitor of several transporters, but it is not clear if ibuprofen is a substrate of any transporter itself. In the present work, we have characterized a transporter of ibuprofen, which is upregulated by hyperosmotic culture conditions in Madin-Darby canine kidney I (MDCK I) renal cells. [(3)H]-Ibuprofen uptake rate was measured in MDCK I cell cultured under normal (300 mOsm) and hyperosmotic (500 mOsm) conditions. Hyperosmotic conditions were obtained by supplementing urea, NaCl, mannitol, or raffinose to culture medium. The effect of increased osmolarity was investigated for different incubation times. [(3)H]-Ibuprofen uptake in MDCK I cells was upregulated by hyperosmotic culture condition, and was saturable with a Km value of 0.37 ± 0.08 μM and a Vmax of 233.1 ± 17.2 pmol· cm(-2)· min(-1). Racemic [(3)H]-ibuprofen uptake could be inhibited by (R)-(-)- and (S)-(+)-ibuprofen with IC50 values of 19 μM (Log IC50 1.39 ± 0.34) and 0.47 μM (Log IC50 -0.36 ± 0.41), respectively. Furthermore, the [(3)H]-ibuprofen uptake rate was increased by decreased extracellular pH but not dependent on Na(+) or Cl(-) ions. The mRNA of Mct1, -2, -4, and -6 as well as Oat1 and -3 were not upregulated by hyperosmolarity. Our findings present strong evidence for the presence of a yet unknown ibuprofen transporter in MDCK I cells. The transporter was upregulated under hyperosmotic culture conditions, and the present study is therefore a starting point for identification of the molecular correlate and potential impact on ibuprofen disposition.
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Carsten Uhd
authors.initials: CU
authors.lastname: Nielsen
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark , Campusvej 55, DK-5230 Odense M, Denmark.
authors.forename: Rune N
authors.initials: RN
authors.lastname: Rasmussen
authors.affiliation: Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Junying
authors.initials: J
authors.lastname: Mo
authors.affiliation: Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Benafsha
authors.initials: B
authors.lastname: Noori
authors.affiliation: Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Candela
authors.initials: C
authors.lastname: Lagunas
authors.affiliation: Pharmaceutical Science and CMC Biologics, H. Lundbeck A/S , DK-2500 Valby, Denmark.
authors.forename: René
authors.initials: R
authors.lastname: Holm
authors.affiliation: Drug Transporters in ADME, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Martha K
authors.initials: MK
authors.lastname: Nøhr
mesh_terms: D000818:Animals; D002460:Cell Line; D004285:Dogs; D007052:Ibuprofen / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells / Q000187:drug effects* / Q000378:metabolism*; D008353:Mannitol / Q000494:pharmacology; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D011887:Raffinose / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
chemical_list: D026901:Membrane Transport Proteins; D008353:Mannitol; D012965:Sodium Chloride; D014508:Urea; D011887:Raffinose; D007052:Ibuprofen
keywords: MDCK 1 cells; ibuprofen; osmolarity; transporter; upregulation