title: Triazolothienopyrimidine inhibitors of urea transporter UT-B reduce urine concentration.
abstract: Urea transport (UT) proteins facilitate the concentration of urine by the kidney, suggesting that inhibition of these proteins could have therapeutic use as a diuretic strategy. We screened 100,000 compounds for UT-B inhibition using an optical assay based on the hypotonic lysis of acetamide-loaded mouse erythrocytes. We identified a class of triazolothienopyrimidine UT-B inhibitors; the most potent compound, UTB(inh)-14, fully and reversibly inhibited urea transport with IC(50) values of 10 nM and 25 nM for human and mouse UT-B, respectively. UTB(inh)-14 competed with urea binding at an intracellular site on the UT-B protein. UTB(inh)-14 exhibited low toxicity and high selectivity for UT-B over UT-A isoforms. After intraperitoneal administration of UTB(inh)-14 in mice to achieve predicted therapeutic concentrations in the kidney, urine osmolality after administration of 1-deamino-8-D-arginine-vasopressin was approximately 700 mosm/kg H(2)O lower in UTB(inh)-14-treated mice than vehicle-treated mice. UTB(inh)-14 also increased urine output and reduced urine osmolality in mice given free access to water. UTB(inh)-14 did not reduce urine osmolality in UT-B knockout mice. In summary, these data provide proof of concept for the potential utility of UT inhibitors to reduce urinary concentration in high-vasopressin, fluid-retaining conditions. The diuretic mechanism of UT inhibitors may complement the action of conventional diuretics, which target sodium transport.
authors.affiliation: Department of Medicine, University of California, San Francisco, USA.
authors.forename: Chenjuan
authors.initials: C
authors.lastname: Yao
authors.forename: Marc O
authors.initials: MO
authors.lastname: Anderson
authors.forename: Jicheng
authors.initials: J
authors.lastname: Zhang
authors.forename: Baoxue
authors.initials: B
authors.lastname: Yang
authors.forename: Puay-Wah
authors.initials: PW
authors.lastname: Phuan
authors.forename: A S
authors.initials: AS
authors.lastname: Verkman
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D003198:Computer Simulation; D057166:High-Throughput Screening Assays; D006801:Humans; D007668:Kidney / Q000502:physiology*; D007671:Kidney Concentrating Ability / Q000502:physiology*; D008297:Male; D026901:Membrane Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D014553:Urinary Tract Physiological Phenomena; D000096982:Urea Transporters
chemical_list: D051398:Aquaporin 1; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D000096982:Urea Transporters; C496021:Aqp1 protein, mouse; C452857:urea transporter B, mouse