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Eur J Pharmacol. 1994 Jan 4;251(1):53-9.

Selective activation of Ca(2+)-dependent K+ channels by novel benzimidazolone.

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Department of Cellular Biology, NeuroSearch A/S, Glostrup, Denmark.


Activators and blockers of specific ion channels are important pharmacological tools for characterizing ion channels and their influence on cell function. The large-conductance Ca(2+)-dependent K+ channel (BK channel) is blocked by peptides such as charybdotoxin and iberiotoxin, but no selective activator of the channel has been described. Here we report single-channel and whole-cell patch-clamp experiments on the specific activation of BK channels in aortic smooth muscle cells with a new heterocyclic molecule, NS 1619 (1-(2'-hydroxy-5'-trifluoromethylphenyl)-5-trifluoromethyl- 2(3H)benzimidazolone). The effect of NS 1619 on the BK channel was dose-dependent, resulting in a shift of the activation curve by up to -50 mV towards negative membrane potentials. The effect was fully reversible and was antagonized by charybdotoxin as well as by tetraethylammonium ions. The compound hyperpolarized the smooth muscle cells. NS 1619 is a selective and new type of K+ channel activator, which may significantly modulate cell excitability.

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