RT Journal Article
SR Electronic
T1 NS19504: A Novel BK Channel Activator with Relaxing Effect on Bladder Smooth Muscle Spontaneous Phasic Contractions
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 520
OP 530
DO 10.1124/jpet.113.212662
VO 350
IS 3
A1 Nausch, Bernhard
A1 Rode, Frederik
A1 Jørgensen, Susanne
A1 Nardi, Antonio
A1 Korsgaard, Mads P. G.
A1 Hougaard, Charlotte
A1 Bonev, Adrian D.
A1 Brown, William D.
A1 Dyhring, Tino
A1 Strøbæk, Dorte
A1 Olesen, Søren-Peter
A1 Christophersen, Palle
A1 Grunnet, Morten
A1 Nelson, Mark T.
A1 Rønn, Lars C. B.
YR 2014
UL http://jpet.aspetjournals.org/content/350/3/520.abstract
AB Large-conductance Ca2+-activated K+ channels (BK, KCa1.1, MaxiK) are important regulators of urinary bladder function and may be an attractive therapeutic target in bladder disorders. In this study, we established a high-throughput fluorometric imaging plate reader–based screening assay for BK channel activators and identified a small-molecule positive modulator, NS19504 (5-[(4-bromophenyl)methyl]-1,3-thiazol-2-amine), which activated the BK channel with an EC50 value of 11.0 ± 1.4 µM. Hit validation was performed using high-throughput electrophysiology (QPatch), and further characterization was achieved in manual whole-cell and inside-out patch-clamp studies in human embryonic kidney 293 cells expressing hBK channels: NS19504 caused distinct activation from a concentration of 0.3 and 10 µM NS19504 left-shifted the voltage activation curve by 60 mV. Furthermore, whole-cell recording showed that NS19504 activated BK channels in native smooth muscle cells from guinea pig urinary bladder. In guinea pig urinary bladder strips, NS19504 (1 µM) reduced spontaneous phasic contractions, an effect that was significantly inhibited by the specific BK channel blocker iberiotoxin. In contrast, NS19504 (1 µM) only modestly inhibited nerve-evoked contractions and had no effect on contractions induced by a high K+ concentration consistent with a K+ channel–mediated action. Collectively, these results show that NS19504 is a positive modulator of BK channels and provide support for the role of BK channels in urinary bladder function. The pharmacologic profile of NS19504 indicates that this compound may have the potential to reduce nonvoiding contractions associated with spontaneous bladder overactivity while having a minimal effect on normal voiding.