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The ionic composition of airway surface liquid and coughing
1Regional Respiratory Physiology Department, Papworth Hospital, Cambridge, England, UK.
Bulletin Europeen De Physiopathologie Respiratoire
|January 1, 1987
Summary
Rapidly-adapting receptors (RARs) in airways respond to ionic changes. Specific reductions in chloride, or extreme pH shifts, stimulate RARs, potentially inducing coughing in humans.
Area of Science:
- Respiratory physiology
- Neuroscience
- Ion channel research
Background:
- Rapidly-adapting receptors (RARs) are located in the laryngeal and tracheal epithelium.
- These receptors in cats and dogs sense changes in airway surface fluid ionic composition.
Purpose of the Study:
- To investigate the ionic and pH thresholds that stimulate RARs.
- To explore the link between RAR stimulation and coughing reflex in humans.
Main Methods:
- Exposing canine laryngeal epithelium to solutions with varying ionic concentrations (Cl-, K+) and pH.
- Observing cough response in humans exposed to nebulized solutions with altered ionic and pH levels.
Main Results:
- RAR stimulation in dogs occurred with [Cl-] < 75 mmol/L, pH < 4 or > 8, and [K+] > 70 mmol/L.
- Human cough reflex was provoked by low [Cl-] or extreme pH (< 4 or > 8) aerosols.
- Increased osmolarity elicited only a minor cough response.
Conclusions:
- The chemical specificity of cough induction in humans mirrors RAR stimulation patterns.
- Changes in airway surface liquid ionic composition likely stimulate RARs, triggering coughing in humans.