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Hypoxia enhances nonspecific bronchial reactivity
The American Review of Respiratory Disease
|October 1, 1985
Summary
Alveolar hypoxia enhances nonspecific bronchial reactivity in sheep, increasing airway sensitivity to histamine and carbachol. This effect, mediated by mast cells, was blocked by cromolyn sodium, suggesting a role for mast cell mediators.
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
- Allergy and Immunology
Background:
- Nonspecific bronchial reactivity is heightened after antigen-induced bronchoconstriction, a mast cell-dependent process.
- Hypoxia is known to trigger mast cell degranulation.
Purpose of the Study:
- To investigate whether alveolar hypoxia induces nonspecific bronchial reactivity.
- To explore the role of mast cells in hypoxia-induced airway hyperresponsiveness.
Main Methods:
- Conscious sheep were exposed to either normoxic air or a hypoxic gas mixture.
- Specific lung resistance (SRL) was measured before and after challenge with histamine or carbachol.
- Experiments were conducted with and without pretreatment with cromolyn sodium.
Main Results:
- Hypoxia alone did not alter SRL but significantly enhanced subsequent increases in SRL induced by histamine and carbachol.
- The enhanced bronchoconstriction following hypoxia was significantly greater than that observed after normoxic exposure.
- Cromolyn sodium pretreatment prevented the hypoxia-induced enhancement of airway responsiveness to histamine and carbachol.
Conclusions:
- Alveolar hypoxia enhances nonspecific bronchial reactivity in sheep.
- This enhancement is likely mediated by mast cell degranulation and the subsequent release of mediators.
- Hypoxia-induced airway hyperresponsiveness may contribute to respiratory conditions involving mast cell activation.