The effect of potassium channel opening drugs on pulmonary nerves

In the present study, the effects of cromakalim were studied in the in vitro innervated tracheal tube preparation. Cromakalim did not affect response of the trachea to exogenous acetylcholine but inhibited contractions of the tracheal preparation to stimulation of cholinergic pulmonary nerves via both transmural and preganglionic vagal stimulation. Glibenclamide significantly reduced the inhibitory effect of cromakalim on both preganglionic and field stimulated preparations. When tracheal tone was raised by a spasmogen, cromakalim had no effect on noradrenergic relaxations but facilitated nonadrenergic-noncholinergic relaxations to transmural stimulation.