An Investigation Into the Mechanism of Inhalation Cough Challenge

Despite its commonplace use in respiratory medicine the mechanism whereby inhalation challenge with a variety of mild acid aerosols produces a dose related and predictable cough is unknown. In this proposal the investigators wish to use established cough challenge methodology to explore the mechanism of action of agents provoking cough both in health and disease. The hypotheses to be tested include: * Intracellular changes in pH, rather than extracellular changes, are key in the activation of TRP receptors, the main sensor for provoking cough. * ATP acting through P2X channels is the mechanism of increased nerve excitability underlying cough hypersensitivity.