Article date: July 2005
By: Stephen A Douglas, David J Behm, Nambi V Aiyar, Diane Naselsky, Jyoti Disa, David P Brooks, Eliot H Ohlstein, John G Gleason, Henry M Sarau, James J Foley, Peter T Buckley, Dulcie B Schmidt, William E Wixted, Katherine Widdowson, Graham Riley, Jian Jin, Timothy F Gallagher, Stanley J Schmidt, Lance Ridgers, Lisa T Christmann, Richard M Keenan, Steven D Knight, Dashyant Dhanak in Volume 145, Issue 5, pages 620-635
SB‐706375 potently inhibited [125I]hU‐II binding to both mammalian recombinant and ‘native’ UT receptors (Ki 4.7±1.5 to 20.7±3.6 nM at rodent, feline and primate recombinant UT receptors and Ki 5.4±0.4 nM at the endogenous UT receptor in SJRH30 cells).
Prior exposure to SB‐706375 (1 μM, 30 min) did not alter [125I]hU‐II binding affinity or density in recombinant cells (KD 3.1±0.4 vs 5.8±0.9 nM and Bmax 3.1±1.0 vs 2.8±0.8 pmol mg−1) consistent with a reversible mode of action.
The novel, nonpeptidic radioligand [3H]SB‐657510, a close analogue of SB‐706375, bound to the monkey UT receptor (KD 2.6±0.4 nM, Bmax 0.86±0.12 pmol mg−1) in a manner that was inhibited by both U‐II isopeptides and SB‐706375 (Ki 4.6±1.4 to 17.6±5.4 nM) consistent with the sulphonamides and native U‐II ligands sharing a common UT receptor binding domain.
SB‐706375 was a potent, competitive hU‐II antagonist across species with pKb 7.29–8.00 in HEK293‐UT receptor cells (inhibition of [Ca2+]i‐mobilization) and pKb 7.47 in rat isolated aorta (inhibition of contraction). SB‐706375 also reversed tone established in the rat aorta by prior exposure to hU‐II (Kapp∼20 nM).
SB‐706375 was a selective U‐II antagonist with 100‐fold selectivity for the human UT receptor compared to 86 distinct receptors, ion channels, enzymes, transporters and nuclear hormones (Ki/IC50>1 μM). Accordingly, the contractile responses induced in isolated aortae by KCl, phenylephrine, angiotensin II and endothelin‐1 were unaltered by SB‐706375 (1 μM).
In summary, SB‐706375 is a high‐affinity, surmountable, reversible and selective nonpeptide UT receptor antagonist with cross‐species activity that will assist in delineating the pathophysiological actions of U‐II in mammals.
SB‐706375 potently inhibited [125I]hU‐II binding to both mammalian recombinant and ‘native’ UT receptors (Ki 4.7±1.5 to 20.7±3.6 nM at rodent, feline and primate recombinant UT receptors and Ki 5.4±0.4 nM at the endogenous UT receptor in SJRH30 cells).
Prior exposure to SB‐706375 (1 μM, 30 min) did not alter [125I]hU‐II binding affinity or density in recombinant cells (KD 3.1±0.4 vs 5.8±0.9 nM and Bmax 3.1±1.0 vs 2.8±0.8 pmol mg−1) consistent with a reversible mode of action.
The novel, nonpeptidic radioligand [3H]SB‐657510, a close analogue of SB‐706375, bound to the monkey UT receptor (KD 2.6±0.4 nM, Bmax 0.86±0.12 pmol mg−1) in a manner that was inhibited by both U‐II isopeptides and SB‐706375 (Ki 4.6±1.4 to 17.6±5.4 nM) consistent with the sulphonamides and native U‐II ligands sharing a common UT receptor binding domain.
SB‐706375 was a potent, competitive hU‐II antagonist across species with pKb 7.29–8.00 in HEK293‐UT receptor cells (inhibition of [Ca2+]i‐mobilization) and pKb 7.47 in rat isolated aorta (inhibition of contraction). SB‐706375 also reversed tone established in the rat aorta by prior exposure to hU‐II (Kapp∼20 nM).
SB‐706375 was a selective U‐II antagonist with 100‐fold selectivity for the human UT receptor compared to 86 distinct receptors, ion channels, enzymes, transporters and nuclear hormones (Ki/IC50>1 μM). Accordingly, the contractile responses induced in isolated aortae by KCl, phenylephrine, angiotensin II and endothelin‐1 were unaltered by SB‐706375 (1 μM).
In summary, SB‐706375 is a high‐affinity, surmountable, reversible and selective nonpeptide UT receptor antagonist with cross‐species activity that will assist in delineating the pathophysiological actions of U‐II in mammals.
British Journal of Pharmacology (2005) 145, 620–635. doi:10.1038/sj.bjp.0706229
DOI: 10.1038/sj.bjp.0706229
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