Non-neurogenic electrically evoked relaxation in canine airway muscle involves action of free radicals on K+ channels.

Cyclopiazonic acid (selective blocker of the internal Ca+2 pump) evoked tonic contraction in canine bronchial smooth muscle (BSM) and tracheal smooth muscle. This contraction was biphasic, including an initial component that was relatively insensitive to blockade of Ca+2 influx (e.g., removal of external Ca+2; nifedipine; hyperpolarization using lemakalim) followed by a component that was sensitive to all such interventions. In BSM, but not in …