The ionic composition of airway surface liquid and coughing.
The rapidly-adapting receptors (RARs) are strategically sited within the paracellular spaces between epithelial cells of the laryngeal and tracheal epithelium. These receptors in cats and dogs appear to respond to changes in the ionic composition of the aqueous fluid bathing the luminal surface of the airway. Studies using dogs and exposing laryngeal epithelium to solutions of differing ionic composition suggest that a reduction in [Cl-] below 75 mmol . l-1 or change in pH, less than 4 and greater than 8 together with a [K+] greater than 70 mmol . l-1 stimulates the (RARs). Coughing can be provoked in man, when breathing ultrasonically nebulized aqueous erosols, with solution low in [Cl-] or when the pH is less than 4 or greater than 8. Only a small response occurs when osmolarity is increased. The similarity of the pattern of chemical specificity of cough to stimulation of RARs suggests that, in man, changes of ionic composition of the airway surface liquid also stimulates RARs and this induces coughing.
Higenbottam
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Regional Respiratory Physiology Department, Papworth Hospital, Cambridge, England, UK.
D000336:Aerosols; D001980:Bronchi / Q000503:physiopathology; D002628:Chemoreceptor Cells / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D003371:Cough / Q000378:metabolism* / Q000503:physiopathology; D004848:Epithelium / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007830:Larynx / Q000378:metabolism*; D010316:Particle Size; D012018:Reflex / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000008:administration & dosage; D014132:Trachea / Q000378:metabolism*
D000336:Aerosols; D002712:Chlorides; D012965:Sodium Chloride; D012964:Sodium; D005947:Glucose