Modulation of sensory nerve function in the airways.

Several clinical studies document a greater discrimination between asthmatic and healthy subjects in bronchial responsiveness to a range of stimuli such as cold air, distilled water and sodium metabisulphite, than to conventional bronchoconstrictor agonists including histamine and methacholine. One of the mechanisms thought to account for the bronchoconstriction induced by these agents is via reflex activation of the cholinergic pathway. An increase in sensory nerve (afferent) activity in asthma might account for the increased responsiveness to these agents. If so, a number of strategies are available to inhibit the function of afferent nerves which could lead to a suppression of bronchial hyperresponsiveness, including (1) inhibition of afferent activity, (2) inhibition of neuropeptide release and (3) antagonism of tachykinin receptors. As there are numerous reviews dealing with the latter, in this review Domenico Spina, Saloni Shah and Selena Harrison focus on the first two strategies.