Cough sensors. II. Transient receptor potential membrane receptors on cough sensors.

The transient receptor potential (TRP) family of channels is represented by at least six members in primary sensory neurons. These include the TRP vanilloid subtypes 1 (TRPV1), 2, 3, and 4, the cold and menthol receptor TRPM8, and TRPA1. Much interest has been directed to the study of the TRPV1, because capsaicin has been instrumental in discovering the unique role of a subset of primary sensory neurons in causing nociceptive responses, in activating reflex pathways including cough, and in producing neurogenic inflammation. TRPV1 is now regarded as an integrator of diverse sensory modalities because it undergoes marked plasticity and sensitization through a variety of mechanisms, including activation of G-protein-coupled or tyrosine kinase receptors. Evidence in experimental animals and in patients with airway diseases indicates a marked hypersensitivity to cough induced by TRPV1 agonists. Recent studies with newly developed high-affinity and selective TRPV1 antagonists have revealed that TRPV1 inhibition reduces cough induced by citric acid or antigen challenge.