Multiple mechanisms of reflex bronchospasm in guinea pigs

Abstract

The mechanisms of histamine- and bradykinin-induced reflex bronchospasm were determined in anesthetized guinea pigs. With intravenous administration, both autacoids evoked dose-dependent increases in tracheal cholinergic tone. Vagotomy or atropine prevented these tracheal reflexes. When delivered as an aerosol, bradykinin readily increased tracheal cholinergic tone, whereas histamine aerosols were much less effective at inducing tracheal reflexes. Also, unlike histamine, bradykinin could evoke profound increases in cholinergic tone without directly or indirectly (e.g., prostanoid dependent) inducing measurable airway smooth muscle contraction resulting in bronchospasm. Neither autacoid requi..