title: Urinary Dopamine as a Potential Index of the Transport Activity of Multidrug and Toxin Extrusion in the Kidney.
abstract: Dopamine is a cationic natriuretic catecholamine synthesized in proximal tubular cells (PTCs) of the kidney before secretion into the lumen, a key site of its action. However, the molecular mechanisms underlying dopamine secretion into the lumen remain unclear. Multidrug and toxin extrusion (MATE) is a H⁺/organic cation antiporter that is highly expressed in the brush border membrane of PTCs and mediates the efflux of organic cations, including metformin and cisplatin, from the epithelial cells into the urine. Therefore, we hypothesized that MATE mediates dopamine secretion, a cationic catecholamine, into the tubule lumen, thereby regulating natriuresis. Here, we show that [³H]dopamine uptake in human (h) MATE1-, hMATE-2K- and mouse (m) MATE-expressing cells exhibited saturable kinetics. Fluid retention and decreased urinary excretion of dopamine and Na⁺ were observed in Mate1-knockout mice compared to that in wild-type mice. Imatinib, a MATE inhibitor, inhibited [³H]dopamine uptake by hMATE1-, hMATE2-K- and mMATE1-expressing cells in a concentration-dependent manner. At clinically-relevant concentrations, imatinib inhibited [³H]dopamine uptake by hMATE1- and hMATE2-K-expressing cells. The urinary excretion of dopamine and Na⁺ decreased and fluid retention occurred in imatinib-treated mice. In conclusion, MATE transporters secrete renally-synthesized dopamine, and therefore, urinary dopamine has the potential to be an index of the MATE transporter activity.
authors.affiliation: Department of Pharmacy, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. motokaji@jsd.med.kyushu-u.ac.jp.
authors.forename: Moto
authors.initials: M
authors.lastname: Kajiwara
authors.affiliation: Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. ban.tsuyoshi.73v@gmail.com.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ban
authors.affiliation: Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Kawaharacho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. kmatsuba@kuhp.kyoto-u.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Matsubara
authors.affiliation: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. yoichi@kokyu.med.kyushu-u.ac.jp.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakanishi
authors.affiliation: Department of Pharmacy, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. satomsdb@pharm.med.kyushu-u.ac.jp.
authors.forename: Satohiro
authors.initials: S
authors.lastname: Masuda
mesh_terms: D000818:Animals; D001692:Biological Transport; D015415:Biomarkers / Q000652:urine*; D002853:Chromatography, Liquid; D004298:Dopamine / Q000493:pharmacokinetics / Q000652:urine*; D057809:HEK293 Cells; D006801:Humans; D000068877:Imatinib Mesylate / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D027701:Organic Cation Transport Proteins / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D053719:Tandem Mass Spectrometry; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; C514424:MATE1 protein, mouse; D027701:Organic Cation Transport Proteins; D047428:Protein Kinase Inhibitors; D000068877:Imatinib Mesylate; D004298:Dopamine
keywords: MATE; dopamine; fluid retention; imatinib; natriuresis