Bronchoconstriction-triggered cough is impaired in typical asthmatics.
OBJECTIVE
Cough is an essential innate protective behavior, which is experienced by even healthy individuals. The mechanism of cough triggered by bronchoconstriction is not yet clear. The aim of this study was to investigate the relation between bronchoconstriction and cough caused by methacholine (Mch) inhalation in typical asthmatics and normal healthy subjects.


METHODS
We measured bronchial responsiveness to Mch and counted the number of coughs induced by Mch inhalation in 15 typical asthmatics and 20 normal subjects.


RESULTS
After inhalation of Mch at the concentration causing 20% or more decrease in forced expiratory volume in 1 second (FEV(1)) (PC(20)-FEV(1)), coughs were provoked in normal subjects (number of cough: 22.5/32 min, range: 3.3-45). Conversely, coughs were hardly provoked in typical asthmatics (median number of cough: 2/32 min, range: 0-4).


CONCLUSIONS
Although typical asthmatics have increased airway responsiveness, their cough response to bronchoconstriction is impaired.
Ohkura
Noriyuki
N
Respiratory Medicine, Kanazawa University Hospital, Ishikawa 920-8641, Japan. nori@med3.m.kanazawa-u.ac.jp
Fujimura
Masaki
M
Tokuda
Akira
A
Nakade
Yusuke
Y
Nishitsuji
Masaru
M
Abo
Miki
M
Katayama
Nobuyuki
N
D000328:Adult; D000368:Aged; D001249:Asthma / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology*; D003371:Cough / Q000139:chemically induced / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D008875:Middle Aged; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
D016210:Methacholine Chloride