Figure 7.

Summary of our findings and a proposed mechanism for the interaction between the adenosine/A₁ receptor and glutamate/GluN1 (NMDA) and the substance P/NK₁ receptor signalling pathways in controlling reflexes such as cough and airway obstruction. Blockade of the A₁ receptor results in an increased cough response and airway obstruction that is reversed following antagonism of the GluN1 and NK₁ receptors. This suggests that stimulation of airway nerves results in an increased central adenosine release which, via the A₁ receptor, limits the cough response possibly by reducing central glutamate and substance P release. We therefore propose that in conditions such as CHS, this cough inhibitory adenosine pathway may be dysfunctional.