Pathophysiology of Airway Afferent Nerves

Vagal afferent nerves provide an airway defense mechanism which is ensured by their activation. These nerves can be activated mechanically mainly through mechanosensitive Aβ fibers which are divided into slowly adapting (SARs) and rapidly adapting stretch receptors (RARs). Chemical activation is provided by an interaction of chemical substances with specific receptors. C-fibers are highly sensitive to a direct chemical stimulation accomplished by an activation of ligand-gated ion channels. According to the large influence and mechanisms of vagal afferent nerves, there is a probability that an inappropriate activity of these nerves can cause the symptoms of the respiratory diseases, e.g. cough, dyspnoea, or airway hyperreactivity. The aim of this review is to summarize the physiology of airway afferent nerves and point out the role of vagal sensory nerves dysfunction in the pathogenesis of some respiratory diseases. The understanding of its mechanism could lead to new therapeutic strategies in patients with airway-related pathology.