STEROIDAL MUSCLE-RELAXANTS ATTENUATE THE CONTRACTILE AND PHOSPHATIDYLINOSITOL RESPONSES OF RAT TRACHEA

Interaction of the steroidal muscle relaxants, pancuronium, vecuronium and rocuronium with airway muscarinic receptors of rat trachea was in vestigated in vitro concerning the contractile and phosphatidylinosito l (PI) responses. Pancuronium and vecuronium attenuated, while rocuron ium did not affect carbachol (CCh)-induced contraction and CCh-induced IP1 accumulation. Pancuronium could inhibit completely CCh-induced co ntraction at a dose of 30 mu M, while it could not inhibit completely CCh-induced IP1 accumulation at the same dose. These drugs attenuated KCl-induced contraction. These results suggest that pancuronium and ve curonium would attenuate airway smooth muscle contraction through the inhibition of muscarinic receptor-mediated PI response, and that the i nhibition of voltage-operated Ca++ channel might be involved, in part, in the attenuation by pancuronium of the contraction.