title: ROMK inhibitor actions in the nephron probed with diuretics.
abstract: Diuretics acting on specific nephron segments to inhibit Na+reabsorption have been used clinically for decades; however, drug interactions, tolerance, and derangements in serum K+complicate their use to achieve target blood pressure. ROMK is an attractive diuretic target, in part, because its inhibition is postulated to indirectly inhibit the bumetanide-sensitive Na+-K+-2Cl-cotransporter (NKCC2) and the amiloride- and benzamil-sensitive epithelial Na+channel (ENaC). The development of small-molecule ROMK inhibitors has created opportunities for exploring the physiological responses to ROMK inhibition. The present study evaluated how inhibition of ROMK alone or in combination with NKCC2, ENaC, or the hydrochlorothiazide (HCTZ) target NCC alter fluid and electrolyte transport in the nephron. The ROMK inhibitor VU591 failed to induce diuresis when administered orally to rats. However, another ROMK inhibitor, termed compound A, induced a robust natriuretic diuresis without kaliuresis. Compound A produced additive effects on urine output and Na+excretion when combined with HCTZ, amiloride, or benzamil, but not when coadministered with bumetanide, suggesting that the major diuretic target site is the thick ascending limb (TAL). Interestingly, compound A inhibited the kaliuretic response induced by bumetanide and HCTZ, an effect we attribute to inhibition of ROMK-mediated K+secretion in the TAL and CD. Compound A had no effect on heterologously expressed flow-sensitive large-conductance Ca2+-activated K+channels (Slo1/β1). In conclusion, compound A represents an important new pharmacological tool for investigating the renal consequences of ROMK inhibition and therapeutic potential of ROMK as a diuretic target.
authors.affiliation: Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Sujay V
authors.initials: SV
authors.lastname: Kharade
authors.affiliation: Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Daniel
authors.initials: D
authors.lastname: Flores
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee.|Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee.|Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee; and.
authors.forename: Craig W
authors.initials: CW
authors.lastname: Lindsley
authors.affiliation: Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Satlin
authors.affiliation: Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee; Jerod.S.Denton@Vanderbilt.edu.|Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee.|Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Jerod S
authors.initials: JS
authors.lastname: Denton
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology*; D002034:Bumetanide / Q000494:pharmacology; D004231:Diuresis / Q000187:drug effects*; D004232:Diuretics / Q000494:pharmacology*; D004347:Drug Interactions; D006852:Hydrochlorothiazide / Q000494:pharmacology; D009399:Nephrons / Q000187:drug effects*; D011188:Potassium / Q000652:urine; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors*; D051381:Rats; D012964:Sodium / Q000652:urine
chemical_list: C000604076:6-nitro-2-((6-nitro-1H-benzimidazol-2-yl)methoxymethyl)-1H-benzimidazole; D001562:Benzimidazoles; D004232:Diuretics; C510692:Kcnj1 protein, rat; D024661:Potassium Channels, Inwardly Rectifying; C013407:benzamil; D006852:Hydrochlorothiazide; D002034:Bumetanide; D000584:Amiloride; D012964:Sodium; D011188:Potassium
keywords: hypertension; mechanism; pharmacology; potassium, sodium