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Structure–activity relationships of bumetanide derivatives: correlation between diuretic activity in dogs and inhibition of the human NKCC 2 A transporter
Author(s) -
Lykke Kasper,
Töllner Kathrin,
Römermann Kerstin,
Feit Peter W,
Erker Thomas,
MacAulay Nanna,
Löscher Wolfgang
Publication year - 2015
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.13231
Subject(s) - bumetanide , chemistry , diuretic , cotransporter , potency , xenopus , transporter , pharmacology , gene isoform , ion transporter , endocrinology , medicine , biochemistry , sodium , biology , in vitro , membrane , organic chemistry , gene
Background and Purpose The N ‐ K ‐ C l cotransporters ( NKCCs ) mediate the coupled, electroneutral movement of Na + , K + and Cl − ions across cell membranes. There are two isoforms of this cation co‐transporter, NKCC 1 and NKCC 2. NKCC 2 is expressed primarily in the kidney and is the target of diuretics such as bumetanide. Bumetanide was discovered by screening ∼5000 3‐amino‐5‐sulfamoylbenzoic acid derivatives, long before NKCC 2 was identified in the kidney. Therefore, structure–activity studies on effects of bumetanide derivatives on NKCC 2 are not available. Experimental Approach In this study, the effect of a series of diuretically active bumetanide derivatives was investigated on human NKCC 2 variant A ( hNKCC2A ) expressed in X enopus laevis oocytes. Key Results B umetanide blocked hNKCC2A transport with an IC 50 of 4 μM. There was good correlation between the diuretic potency of bumetanide and its derivatives in dogs and their inhibition of hNKCC2A ( r 2 = 0.817; P < 0.01). Replacement of the carboxylic group of bumetanide by a non‐ionic residue, for example, an anilinomethyl group, decreased inhibition of hNKCC2A , indicating that an acidic group was required for transporter inhibition. Exchange of the phenoxy group of bumetanide for a 4‐chloroanilino group or the sulfamoyl group by a methylsulfonyl group resulted in compounds with higher potency to inhibit hNKCC2A than bumetanide. Conclusions and Implications The X . laevis oocyte expression system used in these experiments allowed analysis of the structural requirements that determine relative potency of loop diuretics on human NKCC2 splice variants, and may lead to the discovery of novel high‐ceiling diuretics.