ISSN:
1432-1750
Keywords:
Airway hyperresponsiveness
;
Ozone
;
Airway epithelial cell
;
Bronchiole
;
Cat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We examined the effect of exposure to ozone on the epithelium-dependent relaxation (EpDR) of bronchioles evoked by electrical field stimulation (EFS) in a feline model with hyperresponsive airways induced by exposure to ozone. Airway responsiveness was assessed by measuring the increases in total pulmonary resistance (RL) produced by aerosolized acetylcholine (ACh) in vivo. Airway responsiveness was also measured in vitro in dissected bronchiolar ring preparations. Exposure to ozone (3 ppm, 2 h) significantly increased the airway responsiveness in vivo. The concentration of ACh required increasing R L to 200% of the baseline value, decreased from 1.97 mg/ml (GSEM 1.94) to 0.12 mg/ml (GSEM 1.77, p 〈 0.01) after exposure to ozone. EFS evoked atropine-, guanethidine-, and tetrodotoxin-resistant relaxations in the control bronchiolar rings precontracted by 5-hydroxytryptamine. Such relaxation was significantly suppressed by the mechanical denudation of epithelium, confirming that it was epithelium dependent. The amplitude of EpDR was significantly suppressed in the animals exposed to ozone. These results suggest that EpDR is present in cats, and that its inhibition may contribute to the development of airway hyperresponsiveness.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00167600
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