There appears to be a close interrelationship among airway responsiveness to mediators
and to natural stimuli, the presence and severity of asthma, and endogenous mediator
release in the airways. Histamine and methacholine have been most commonly used to
measure airway responsiveness. Airway responsiveness to the two drugs is increased in
patients with current symptoms of asthma, and the degree of increase relates closely to the
degree of variable airflow obstruction and the therapy to control symptoms. The degree of …