title: Allergen-induced hyperresponsiveness to bradykinin is more pronounced than that to methacholine.
abstract: Bradykinin reduces airflow in asthmatic patients via indirect mechanism(s), possibly involving sensory nerve stimulation and increased vascular permeability. We hypothesized that allergen inhalation, which affects reactivity of nerves and vessels, would differentially alter reactivity to bradykinin and the smooth muscle spasmogen methacholine. We compared reactivity to methacholine and bradykinin 1, 2, 4, 7, 11, and 14 days after allergen provocation in 12 atopic asthmatic patients with stable baseline reactivity to bradykinin. Maximal allergen-induced shifts from baseline in reactivity were 0.73 +/- 0.12 log unit for bradykinin compared with 0.27 +/- 0.13 log units for methacholine (P = 0.0005). Nine subjects showed significant increases in bradykinin reactivity, with four subjects increasing reactivity by > 1 log unit. Moreover, the maximal mean change in bradykinin reactivity occurred 2 days postallergen. Thus, allergen-induced changes in reactivity to bradykinin and methacholine differ in magnitude and time course. Bradykinin inhalational challenge provides a sensitive index of the airway's response to allergen.
authors.affiliation: Department of Medicine, Johns Hopkins Asthma and Allergy Center, Baltimore, Maryland 21224-6801, USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Berman
authors.forename: A G
authors.initials: AG
authors.lastname: Togias
authors.forename: G
authors.initials: G
authors.lastname: Skloot
authors.forename: D
authors.initials: D
authors.lastname: Proud
mesh_terms: D000328:Adult; D000485:Allergens / Q000494:pharmacology*; D001249:Asthma / Q000503:physiopathology*; D001920:Bradykinin / Q000494:pharmacology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D003371:Cough / Q000139:chemically induced / Q000503:physiopathology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology*; D008875:Middle Aged; D013147:Spirometry
chemical_list: D000485:Allergens; D016210:Methacholine Chloride; D001920:Bradykinin