On the Pharmacological and Physiological Role of Glibenclamide‐Sensitive Potassium Channels in Colonic Smooth Muscle

Abstract: Actions of activators of glibenclamide sensitive K+ channels on canine colonic circular muscle were investigated. Cromakalim as well as its (‐) enantiomer lemakalim caused inhibition of spontaneous phasic contractile activity (EC50's 4.4 ± 0.1 × 10‐7 M and 2.3 ± 0.4 × 10‐7 M, respectively) and of carbachol induced activity (EC50's: 9.4 ± 5.1 × 10‐7 M and 4.3 ± 1.4 × 10‐7 M, respectively). Cromakalim and lemakalim effects were completely inhibited by glibenclamide. Additive effects between K+ channel activators and other drugs relaxing colonic muscle (the L‐type calcium channel blocker D600 and forskolin) were seen. A physiological role for specific glibenclamide sensitive K+ channels, if existing, remains unresolved. The present study indicates that the non‐adrenergic inhibitory nerves do not act through these channels, neither does stimulation of muscarinic or β‐adrenergic receptors.

On the Pharmacological and Physiological Role of Glibenclamide‐Sensitive Potassium Channels in Colonic Smooth Muscle Journal Articles