Diuresis and reduced urinary osmolality in rats produced by small-molecule UT-A-selective urea transport inhibitors.

Abstract

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.

• Authors: Cristina Esteva-Font, Onur Cil, Puay-Wah Phuan, Tao Su, Sujin Lee, Marc O Anderson, A S Verkman
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 28 Issue 9 Pg. 3878-90 (Sep 2014) ISSN: 1530-6860 [Electronic] United States
• PMID: 24843071 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © FASEB.

Chemical References

• Membrane Transport Proteins
• Small Molecule Libraries
• Sodium Chloride

Topics

• Animals
• Biological Transport (drug effects)
• Chromatography, Liquid
• Diuresis (drug effects, physiology)
• Dogs
• High-Throughput Screening Assays
• Kidney Concentrating Ability (drug effects)
• Madin Darby Canine Kidney Cells
• Male
• Membrane Transport Proteins (chemistry, metabolism)
• Models, Molecular
• Osmolar Concentration
• Rats
• Rats, Wistar
• Small Molecule Libraries (chemical synthesis, pharmacokinetics, pharmacology)
• Sodium Chloride
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• Structure-Activity Relationship
• Tissue Distribution
• Urinary Tract (drug effects, metabolism)
• Urine (chemistry)
• Urea Transporters