Potentiating effect of inhaled acetaldehyde on bronchial responsiveness to methacholine in asthmatic subjects.
BACKGROUND
It has recently been reported that acetaldehyde induces bronchoconstriction indirectly via histamine release. However, no study has been performed to assess whether acetaldehyde worsens bronchial responsiveness in asthmatic subjects so this hypothesis was tested.


METHODS
Methacholine provocation was performed on three occasions: (1) after pretreatment with oral placebo and inhaled saline (P-S day), (2) after placebo and inhaled acetaldehyde (P-A day), and (3) after a potent histamine H1 receptor antagonist terfenadine and acetaldehyde (T-A day) in a double blind, randomised, crossover fashion. Nine asthmatic subjects inhaled 0.8 mg/ml acetaldehyde or saline for four minutes. After each inhalation a methacholine provocation test was performed.


RESULTS
Methacholine concentrations producing a 20% fall in FEV1 (PC20-MCh) on the P-A day (0.48 mg/ml, 95% CI 0.21 to 1.08) and T-A day (0.41 mg/ml, 95% CI 0.22 to 0.77) were lower than those on the P-S day (0.85 mg/ml, 95% CI 0.47 to 1.54). There was no change in the PC20-MCh between the P-A and T-A days. A correlation was observed between the logarithmic values of PC20-MCh (log PC20-MCh) on the P-S day and the potentiating effect of acetaldehyde on the methacholine responsiveness [(log PC20-MCh on P-A day)-(log PC20-MCh on P-S day)] (rho = 0.82).


CONCLUSIONS
Acetaldehyde induces bronchial hyperresponsiveness in patients with asthma by mechanisms other than histamine release.
Myou
S
S
Division of Respiratory Medicine, Ishikawa Prefectural Central Hospital, Kanazawa, Japan.
Fujimura
M
M
Nishi
K
K
Matsuda
M
M
Ohka
T
T
Matsuda
T
T
D000079:Acetaldehyde; D000328:Adult; D000368:Aged; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000139:chemically induced*; D001985:Bronchial Provocation Tests; D004311:Double-Blind Method; D004357:Drug Synergism; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D016593:Terfenadine
D016210:Methacholine Chloride; D016593:Terfenadine; D000079:Acetaldehyde