Effect of high dose inhaled acetic acid on airway responsiveness in Fischer rats.
BACKGROUND
Sudden, severe airway injury has been associated with an acute, and at times persisting, airway hyper-responsiveness with clinical features of asthma, termed reactive airways dysfunction syndrome (RADS). An attempt was made to develop a rat model of RADS by exposing inbred Fischer rats to inhaled 8 N acetic acid for 2 mins (13 N inhalation was lethal).


METHODS
Lung resistance (RL) and lung elastance (EL) were measured in 14 eight- to 10-week old male rats. Baseline responsiveness to methacholine was quantified by calculating the dose required for doubling of RL. The next day, the study group (n=11) was exposed to aerosolized acetic acid. Control animals (n=3) were similarly exposed to buffered saline solution.


RESULTS
Acetic acid exposure resulted in a significant (P<0.02) increase in RL (by 80%) and EL (by 67%), lasting less than 10 mins postexposure, but no significant change in methacholine responsiveness at one day and seven days postexposure.


CONCLUSIONS
Failure to induce persistent airway hyper-responsiveness may relate to the choice of animal, choice of irritant, or insufficient level or duration of exposure, or may reflect a lack of individual predisposing cofactors such as smoking or underlying asthmatic predisposition.
Ariel
A P
AP
Department of Medicine, University of Toronto, Toronto, Canada.
Furlott
H G
HG
Chapman
K R
KR
Slutsky
A S
AS
Webster
P
P
Zamel
N
N
Tarlo
S M
SM
D019342:Acetic Acid / Q000008:administration & dosage* / Q000633:toxicity; D000280:Administration, Inhalation; D000336:Aerosols; D000403:Airway Resistance / Q000187:drug effects; D000818:Animals; D001249:Asthma / Q000139:chemically induced* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000139:chemically induced* / Q000503:physiopathology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D015656:Respiratory Mechanics
D000336:Aerosols; D019342:Acetic Acid