Article (Scientific journals)
Chronic exposure to ozone causes tolerance to airway hyperresponsiveness in guinea pigs: lack of SOD role.
Vargas, M. H.; Romero, L.; Sommer, B. et al.
1998In Journal of Applied Physiology, 84 (5), p. 1749-1755
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Keywords :
superoxide dismutase; adaptation; airway inflammation
Abstract :
[en] Tolerance to respiratory effects of O3 has been demonstrated for anatomic and functional changes, but information about tolerance to O3-induced airway hyperresponsiveness (AHR) is scarce. In guinea pigs exposed to air or O3 (0.3 parts/million, 4 h/day, for 1, 3, 6, 12, 24, or 48 days, studied 16-18 h later), pulmonary insufflation pressure changes induced by intravenous substance P (SP, 0.032-3.2 micro ug/kg) were measured, then the animals were subjected to bronchoalveolar lavage (BAL). Bronchial rings with or without phosphoramidon were also evaluated 3 h after air or a single O3 exposure. O3 caused in vivo AHR (increased sensitivity) to SP after 1, 3, 6, 12, and 24 days of exposure compared with control. However, after 48 days of exposure, O3 no longer caused AHR. Total cell, macrophage, neutrophil, and eosinophil counts in BAL were increased in most O3-exposed groups. When data from all animals were pooled, we found a highly significant correlation between degree of airway responsiveness and total cells (r = 0.55), macrophages (r = 0.54), neutrophils (r = 0.47), and eosinophils (r = 0.53), suggesting that airway inflammation is involved in development of AHR to SP. Superoxide dismutase (SOD) levels in BAL fluids were increased (P < 0.05) after 1, 3, 6, and 12 days of O3 exposure and returned to basal levels after 24 and 48 days of exposure. O3 failed to induce hyperresponsiveness to SP in bronchial rings, and phosphoramidon increased responses to SP in air- and O3-exposed groups, suggesting that neutral endopeptidase inactivation was not involved in O3-induced AHR to SP in vivo. We conclude that chronic exposure to 0. 3 ppm O3, a concentration found in highly polluted cities, resulted in tolerance to AHR to SP in guinea pigs by an SOD-independent mechanism.
Disciplines :
Veterinary medicine & animal health
Author, co-author :
Vargas, M. H.
Romero, L.
Sommer, B.
Zamudio, P.
Gustin, Pascal ;  Université de Liège - ULiège > Département de sciences fonctionnelles > Pharmacologie, pharmacothérapie et toxicologie
Montano, L. M.
Language :
English
Title :
Chronic exposure to ozone causes tolerance to airway hyperresponsiveness in guinea pigs: lack of SOD role.
Publication date :
1998
Journal title :
Journal of Applied Physiology
ISSN :
8750-7587
eISSN :
1522-1601
Publisher :
American Physiological Society, Bethesda, United States - Maryland
Volume :
84
Issue :
5
Pages :
1749-1755
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 12 March 2009

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