PH-dependent transport kinetics of the human organic anion-transporting polypeptide 1A2. Issue 2 (April 2020)

• Record Type: Journal Article
• Authors: Morita, Tokio; Akiyoshi, Takeshi; Sato, Ryo; Katayama, Kazuhiro; Yajima, Kodai; Kataoka, Hiroki; Imaoka, Ayuko; Sugimoto, Yoshikazu; Ohtani, Hisakazu
• Is Part Of: Drug metabolism and pharmacokinetics. Volume 35:Issue 2(2020)
• Page Start: 220
• Page End: 227
• Publication Date: 2020-04
• Subjects: OATP1A2 -- pH-dependency -- Multiple binding site -- Uptake transporter; BCA Bicinchoninic acid -- BSP Sulfobromophthalein -- CL Clearance -- DMSO Dimethyl sulfoxide -- FCCP Carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone -- HBSS Hank's balanced salt solution -- HEK293 Human embryonic kidney 293 -- HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid -- MBS Multiple binding site -- MES 2-(N-morpholino)ethanesulfonic acid -- OATP Organic anion transporting polypeptide -- SLC Solute carrier -- TBS-T Tris-buffered saline containing 0.05% Tween 20; Drugs -- Metabolism -- Periodicals; Pharmacokinetics -- Periodicals; 615.7
• DOI: 10.1016/j.dmpk.2019.12.002
• Languages: English
• ISSNs: 1347-4367

Abstract

Abstract: Organic anion-transporting polypeptide (OATP) 1A2 is expressed on the apical sides of intestinal and renal epithelial cells and considered to be involved in the intestinal absorption and renal reabsorption of drugs. Although the transport activity of OATP1A2 is considered to be pH-dependent, the effects of pH on its kinetic parameters and on the potency of OATP1A2 inhibitors are yet to be elucidated. Some OATP are known to have multiple binding sites (MBS), but it remains unclear whether OATP1A2 has MBS. In the present study, we evaluated the influence of pH on the OATP1A2-mediated uptake of estrone 3-sulfate using OATP1A2-expressing HEK293 cells. The uptake of 0.3 μM estrone 3-sulfate by HEK293-OATP1A2 cells was pH-dependent. OATP1A2 exhibited bimodal saturation kinetics at pH 6.3 and 7.4. Compared with that seen at pH 6.3 (5.62 μM), the K m value of the high-affinity site was 8-fold higher at pH 7.4 (43.2 μM). In addition, the influence of pH on the potency of inhibitors varied among the examined inhibitors. These results suggest that the transport properties of OATP1A2 under lower pH conditions, such as those found in the microenvironments of the small intestinal mucosa and distal tubules, differ from those seen under neutral pH conditions. Graphical abstract: Image 1