The effect of adrenergic and cholinergic drugs on methacholine- and histamine-induced bronchoconstriction in monkeys

The effect of adrenergic and cholinergic drugs on bronchial contraction of monkeys was studied using bronchoconstriction induced by aerosol challenge with methacholine and histamine. Under the anesthesia with ketamine hydrochloride, changes in the total respiratory resistance were continuously measured in monkeys to estimate the bronchial response to both histamine and methacholine. Isoprenaline decreased bronchial susceptibility to aerosol challenge with both methacholine and histamine. Isoprenaline was also potent in antagonizing the bronchoconstriction induced by methacholine and histamine. Atropine decreased bronchial susceptibility to aerosol challenge with methacholine and also partially with histamine. Atropine also antagonized the bronchoconstriction induced by methacholine, but not by histamine. Phentolamine had neither inhibitory effects on the aerosol challenge with methacholine and histamine, nor produced an antagonistic effect on bronchoconstriction induced with methacholine and histamine.