Diuresis and reduced urinary osmolality in rats produced by small-molecule UT-A-selective urea transport inhibitors.
Urea transport (UT) proteins of the UT-A class are expressed in epithelial cells in kidney tubules, where they are required for the formation of a concentrated urine by countercurrent multiplication. Here, using a recently developed high-throughput assay to identify UT-A inhibitors, a screen of 50,000 synthetic small molecules identified UT-A inhibitors of aryl-thiazole, γ-sultambenzosulfonamide, aminocarbonitrile butene, and 4-isoxazolamide chemical classes. Structure-activity analysis identified compounds that inhibited UT-A selectively by a noncompetitive mechanism with IC50 down to ∼1 μM. Molecular modeling identified putative inhibitor binding sites on rat UT-A. To test compound efficacy in rats, formulations and administration procedures were established to give therapeutic inhibitor concentrations in blood and urine. We found that intravenous administration of an indole thiazole or a γ-sultambenzosulfonamide at 20 mg/kg increased urine output by 3-5-fold and reduced urine osmolality by ∼2-fold compared to vehicle control rats, even under conditions of maximum antidiuresis produced by 1-deamino-8-D-arginine vasopressin (DDAVP). The diuresis was reversible and showed urea > salt excretion. The results provide proof of concept for the diuretic action of UT-A-selective inhibitors. UT-A inhibitors are first in their class salt-sparing diuretics with potential clinical indications in volume-overload edemas and high-vasopressin-associated hyponatremias.
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and.
Cristina
C
Esteva-Font
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and.
Onur
O
Cil
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and.
Puay-Wah
PW
Phuan
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and.
Tao
T
Su
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and.
Sujin
S
Lee
Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California, USA.
Marc O
MO
Anderson
Department of Medicine and Department of Physiology, University of California, San Francisco, California, USA and alan.verkman@ucsf.edu.
A S
AS
Verkman
D000818:Animals; D001692:Biological Transport / Q000187:drug effects*; D002853:Chromatography, Liquid; D004231:Diuresis / Q000187:drug effects* / Q000502:physiology; D004285:Dogs; D057166:High-Throughput Screening Assays; D007671:Kidney Concentrating Ability / Q000187:drug effects*; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009994:Osmolar Concentration; D051381:Rats; D017208:Rats, Wistar; D054852:Small Molecule Libraries / Q000138:chemical synthesis / Q000493:pharmacokinetics / Q000494:pharmacology*; D012965:Sodium Chloride; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship; D014018:Tissue Distribution; D014551:Urinary Tract / Q000187:drug effects / Q000378:metabolism; D014556:Urine / Q000737:chemistry*; D000096982:Urea Transporters
D026901:Membrane Transport Proteins; D054852:Small Molecule Libraries; D012965:Sodium Chloride; D000096982:Urea Transporters
diuretic; drug discovery; kidney