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Cross refractoriness between sodium metabisulphite and exercise induced asthma
I Pavord1, H Lazarowicz, D Inchley
1Respiratory Medicine Unit, City Hospital, Nottingham, UK.
Thorax
|March 1, 1994
Summary
Exercise and sodium metabisulphite cause asthma bronchoconstriction. Repeat challenges lead to refractoriness, suggesting a shared mechanism. This study found cross-refractoriness between these stimuli in asthma patients.
Area of Science:
- Respiratory Medicine
- Pulmonary Physiology
- Asthma Pathophysiology
Background:
- Exercise and inhaled sodium metabisulphite can trigger bronchoconstriction in asthma.
- The mechanism behind the refractory period following repeated challenges is not fully understood.
- Prostaglandin release is a potential shared pathway for refractoriness.
Purpose of the Study:
- To investigate if exercise and sodium metabisulphite-induced bronchoconstriction share a common refractory mechanism.
- To determine the degree of cross-refractoriness between these two stimuli in mild asthma.
Main Methods:
- Thirteen mild asthma patients with established exercise and sodium metabisulphite bronchoconstriction were studied.
- Subjects underwent repeated challenges with either exercise or sodium metabisulphite, and cross-over challenges.
- Lung function (FEV1) was measured to assess the degree of bronchoconstriction and refractoriness.
Main Results:
- A significant reduction in exercise-induced bronchoconstriction was observed after a prior exercise challenge (62.3%) and after sodium metabisulphite challenge (50.7%).
- Sodium metabisulphite-induced bronchoconstriction was significantly reduced after a prior sodium metabisulphite challenge (80.2%) and after exercise challenge (37.3%).
Conclusions:
- The findings suggest a partially shared mechanism underlying refractoriness to both exercise and sodium metabisulphite in asthma.
- Cross-refractoriness indicates a common pathway, potentially involving inhibitory prostaglandins, in the response to these stimuli.