title: Salt-sparing diuretic action of a water-soluble urea analog inhibitor of urea transporters UT-A and UT-B in rats.
abstract: Inhibitors of kidney urea transporter (UT) proteins have potential use as salt-sparing diuretics ('urearetics') with a different mechanism of action than diuretics that target salt transporters. To study UT inhibition in rats, we screened about 10,000 drugs, natural products and urea analogs for inhibition of rat UT-A1. Drug and natural product screening found nicotine, sanguinarine and an indolcarbonylchromenone with IC50 of 10-20 μM. Urea analog screening found methylacetamide and dimethylthiourea (DMTU). DMTU fully and reversibly inhibited rat UT-A1 and UT-B by a noncompetitive mechanism with IC50 of 2-3 mM. Homology modeling and docking computations suggested DMTU binding sites on rat UT-A1. Following a single intraperitoneal injection of 500 mg/kg DMTU, peak plasma concentration was 9 mM with t1/2 of about 10 h, and a urine concentration of 20-40 mM. Rats chronically treated with DMTU had a sustained, reversible reduction in urine osmolality from 1800 to 600 mOsm, a 3-fold increase in urine output, and mild hypokalemia. DMTU did not impair urinary concentrating function in rats on a low protein diet. Compared to furosemide-treated rats, the DMTU-treated rats had greater diuresis and reduced urinary salt loss. In a model of syndrome of inappropriate antidiuretic hormone secretion, DMTU treatment prevented hyponatremia and water retention produced by water-loading in dDAVP-treated rats. Thus, our results establish a rat model of UT inhibition and demonstrate the diuretic efficacy of UT inhibition.
authors.affiliation: 1] Departments of Medicine and Physiology, University of California, San Francisco, CA, USA [2] Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara, Turkey.
authors.forename: Onur
authors.initials: O
authors.lastname: Cil
authors.affiliation: Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
authors.forename: Cristina
authors.initials: C
authors.lastname: Esteva-Font
authors.affiliation: Department of Pharmacology, Hacettepe University Faculty of Medicine, Ankara, Turkey.
authors.forename: Sadik Taskin
authors.initials: ST
authors.lastname: Tas
authors.affiliation: Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Su
authors.affiliation: Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
authors.forename: Sujin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA.
authors.forename: Marc O
authors.initials: MO
authors.lastname: Anderson
authors.affiliation: Department of Pharmacology, Hacettepe University Faculty of Medicine, Ankara, Turkey.
authors.forename: Mert
authors.initials: M
authors.lastname: Ertunc
authors.affiliation: Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Verkman
mesh_terms: D000818:Animals; D001665:Binding Sites; D004195:Disease Models, Animal; D004231:Diuresis / Q000187:drug effects*; D004232:Diuretics / Q000494:pharmacology; D004285:Dogs; D004353:Drug Evaluation, Preclinical; D005260:Female; D005665:Furosemide / Q000494:pharmacology; D007008:Hypokalemia / Q000139:chemically induced; D007010:Hyponatremia / Q000209:etiology / Q000517:prevention & control; D007177:Inappropriate ADH Syndrome / Q000150:complications / Q000188:drug therapy; D020128:Inhibitory Concentration 50; D061985:Madin Darby Canine Kidney Cells; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000652:urine*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D013997:Time Factors; D014556:Urine / Q000737:chemistry; D000096982:Urea Transporters
chemical_list: D004232:Diuretics; D005665:Furosemide; D026901:Membrane Transport Proteins; D012965:Sodium Chloride; D013890:Thiourea; D000096982:Urea Transporters; C038983:1,3-dimethylthiourea