title: Atenolol Renal Secretion Is Mediated by Human Organic Cation Transporter 2 and Multidrug and Toxin Extrusion Proteins.
abstract: Atenolol is a β-blocker widely used in the treatment of hypertension. Atenolol is cleared predominantly by the kidney by both glomerular filtration and active secretion, but the molecular mechanisms involved in its renal secretion are unclear. Using a panel of human embryonic kidney cell lines stably expressing human organic cation transporter (hOCT) 1-3, human organic anion transporter (hOAT) 1, hOAT3, human multidrug and toxin extrusion protein (hMATE) 1, and hMATE2-K, we found that atenolol interacted with both organic cation and anion transporters. However, it is transported by hOCT1, hOCT2, hMATE1, and hMATE2-K, but not by hOCT3, hOAT1, and hOAT3. A detailed kinetic analysis coupled with absolute quantification of membrane transporter proteins by liquid chromatography-tandem mass spectrometry revealed that atenolol is an excellent substrate for the renal transporters hOCT2, hMATE1, and hMATE2-K. The Km values for hOCT2, hMATE1, and hMATE2-K are 280 ± 4, 32 ± 5, and 76 ± 14 μM, respectively, and the calculated turnover numbers are 2.76, 0.41, and 2.20 s(-1), respectively. To demonstrate unidirectional transepithelial transport of atenolol, we developed and functionally validated a hOCT2/hMATE1 double-transfected Madin-Darby canine kidney cell culture model. Transwell studies showed that atenolol transport in the basal (B)-to-apical (A) direction is 27-fold higher than in the A-to-B direction, whereas its B-to-A/A-to-B transport ratio was only 2 in the vector-transfected control cells. The overall permeability of atenolol in the B-to-A direction in hOCT2/hMATE1 cells was 44-fold higher than in control cells. Together, our data support that atenolol tubular secretion is mediated through the hOCT2/hMATEs secretion pathway and suggest a significant role of organic cation transporters in the disposition of an important antihypertensive drug.
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington.
authors.forename: Jia
authors.initials: J
authors.lastname: Yin
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington.
authors.forename: Haichuan
authors.initials: H
authors.lastname: Duan
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shirasaka
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington.
authors.forename: Bhagwat
authors.initials: B
authors.lastname: Prasad
authors.affiliation: Department of Pharmaceutics, University of Washington, Seattle, Washington jowang@uw.edu.
authors.forename: Joanne
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001262:Atenolol / Q000378:metabolism* / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells; D029362:Organic Anion Transporters, Sodium-Independent / Q000037:antagonists & inhibitors / Q000502:physiology*; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D029362:Organic Anion Transporters, Sodium-Independent; D027701:Organic Cation Transport Proteins; C490280:SLC22A7 protein, human; C521869:SLC47A1 protein, human; C521870:SLC47A2 protein, human; D001262:Atenolol