Action of a novel potassium channel opener, SR 47063, on human bronchi and on guinea-pig trachea in vitro: comparison with cromakalim

Potassium channels are present on airway smooth muscle cells and their activation results in hyperpolarization and relaxation. Because these effects may have therapeutic relevance to asthma, the aim of our study was to examine the activity of SR 47063, a potassium channel opener (KCO), against a variety of spasmogens or against electrical field stimulation in guinea‐pig isolated trachea and in human isolated bronchi in vitro; the effects of SR 47063 were compared with those of cromakalim, isoprenaline, and theophylline. Like cromakalim, SR 47063 reduced the contractility of guinea‐pig isolated trachea and the human isolated bronchus in basal tone with pD2 of 7.79 ± 0.01 and 7.83 ± 0.09, respectively, or during precontractions induced by acetylcholine 10−4 M, histamine 10−5 M, or low concentrations of KCl (