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Cross refractoriness between sodium metabisulphite and exercise induced asthma.

Abstract:
BACKGROUND: Exercise and inhaled sodium metabisulphite are thought to cause bronchoconstriction in asthma through different mechanisms. The response to both stimuli becomes refractory with repeat challenge. The mechanism of refractoriness is unclear, although depletion of mast cell derived mediators or neurotransmitters has been suggested. Recent studies suggest a common mechanism involving release of inhibitory prostaglandins. If this is true, exercise and sodium metabisulphite induced bronchoconstriction should show cross refractoriness. METHODS: Thirteen subjects with mild asthma and previously established exercise and sodium metabisulphite induced bronchoconstriction performed two sodium metabisulphite challenges (giving a single dose previously shown to cause a 20% fall in FEV1) on one study day, and two exercise tests on another. The second challenge proceeded after recovery (FEV1 > 95% baseline) from the first. Subjects then attended on two further occasions when an exercise test was performed after sodium metabisulphite and a sodium metabisulphite challenge after exercise. RESULTS: When expressed as the percentage reduction in the area under the change in percentage FEV1 curve over 20 minutes (AUC) the response to exercise was reduced by a mean 62.3% (95% CI 46.5% to 78.1%) following a first exercise challenge, and by 50.7% (95% CI 27.8% to 73.6%) following a sodium metabisulphite challenge. The response to a sodium metabisulphite challenge was reduced by a mean of 80.2% (95% CI 68.9% to 91.5%) when it followed a sodium metabisulphite challenge, and by 37.3% (95% CI 15.1% to 59.5%) following an exercise challenge. CONCLUSION: This study shows some cross refractoriness between exercise and sodium metabisulphite induced bronchoconstriction, in keeping with a partially shared mechanism of refractoriness.

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Publisher copy:
10.1136/thx.49.3.245

Authors

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Institution:
University of Oxford
Division:
MSD
Department:
NDM
Role:
Author


Journal:
Thorax More from this journal
Volume:
49
Issue:
3
Pages:
245-249
Publication date:
1994-03-01
DOI:
EISSN:
1468-3296
ISSN:
0040-6376


Language:
English
Keywords:
Pubs id:
pubs:435410
UUID:
uuid:1157c26d-e663-435e-abde-548a0c493e72
Local pid:
pubs:435410
Source identifiers:
435410
Deposit date:
2013-11-16
ARK identifier:

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