title: An ESR contrast agent is transported to rat liver through organic anion transporter.
abstract: Carboxy PROXYL is a useful extracellular paramagnetic contrast reagent in electron spin resonance (ESR) and magnetic resonance imaging (MRI). Active transfer of the probe was investigated using an in situ liver model in rats. Carboxy PROXYL, a nitroxyl spin probe, was perfused into in situ liver perfusion system from Wistar rats. Concentration of nitroxyl form of the spin probe in effluent increased gradually after introducing perfusate with the spin probe and reached a plateau. The disappearance of Carboxy PROXYL from the perfusate was 40%, which could not be explained with its partition coefficient. Administration of non-selective inhibitors of organic anion transporters, p-aminohippuric acid and penicillin G, inhibited competitively and in a dose dependent manner the transfer of Carboxy PROXYL into rat liver in situ, resulting in increases of Carboxy PROXYL in the effluent. The results demonstrate that there is an active transfer system of an ESR contrast reagent into in situ rat liver through organic anion transporters.
authors.affiliation: Department of Bio-function Analysis, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-Ku, Fukuoka 812-8582, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Sato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondo
authors.forename: Hideo
authors.initials: H
authors.lastname: Utsumi
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D003287:Contrast Media / Q000378:metabolism* / Q000493:pharmacokinetics*; D004578:Electron Spin Resonance Spectroscopy; D008099:Liver / Q000378:metabolism*; D027361:Organic Anion Transporters / Q000378:metabolism*; D051381:Rats; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D027361:Organic Anion Transporters; D013113:Spin Labels