Non-Adrenergic Non-Cholinergic Neurotransmission in the Airways: Role of Nitric Oxide

Autonomic nerves regulate several aspects of airway function [1]. However, for the purposes of this chapter, we will focus on the role of nitric oxide (NO)-containing nerves in the control of airway smooth muscle function. Neural control of airway smooth muscle is very complex since in addition to cholinergic and adrenergic innervation there is a non-adrenergic non-cholinergic (NANC) innervation. The existence of a NANC nervous system in the gastrointestinal tract, which controls gut motility, sphincters and secretions had previously been established in vertebrates from fish to humans [2]. The airways develop embryologically from the foregut and so the existence of NANC nerves in the respiratory tract was not an unexpected finding.