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Bronchoconstrictor response to inhaled capsaicin in humans
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1985
Summary
Inhaled capsaicin causes dose-dependent airway constriction in humans, affecting normal, smoking, and asthmatic individuals similarly. This bronchoconstriction is mediated by a vagal reflex, not substance P, and is reduced by ipratropium bromide.
Area of Science:
- Respiratory Medicine
- Neuroscience
- Pharmacology
Background:
- Capsaicin, derived from chili peppers, is known to activate sensory nerves.
- Airway tone regulation involves complex neural pathways, including vagal reflexes.
Purpose of the Study:
- To investigate the effects of inhaled capsaicin on human airway tone.
- To determine the mechanism underlying capsaicin-induced bronchoconstriction.
Main Methods:
- Healthy, smoking, and asthmatic subjects inhaled capsaicin in varying doses.
- Airway conductance was measured before and after capsaicin exposure.
- The effects of ipratropium bromide and sodium cromoglycate on capsaicin response were assessed.
Main Results:
- Inhaled capsaicin caused a dose-dependent, transient fall in specific airway conductance.
- Bronchoconstriction magnitude and duration were similar across normal, smoking, and asthmatic subjects.
- Ipratropium bromide significantly attenuated the response, suggesting a cholinergic vagal reflex.
Conclusions:
- Inhaled capsaicin is a potent stimulus for bronchoconstriction in humans.
- The response is mediated by a vagal reflex, not substance P release.
- Capsaicin serves as a valuable tool for studying nonmyelinated nerve reflexes in airways.