Afferent receptors in the airways and cough

The roles of airway rapidly adapting receptors (RARs) and of C-fibre recept ors in the induction of cough are reviewed. It is concluded that, while the re is substantial evidence that irritant receptors in the laryngeal wall an d RARs in the tracheobronchial mucosa can cause cough, the evidence for suc h a similar direct role for C-fibre receptors is tenuous. Indeed there is a ccumulating evidence that the C-fibre receptors may cause apnoea and rapid shallow breathing, and also reflexly inhibit cough. However the C-fibre rec eptors may release tachykinins when stimulated, and these in turn may cause plasma extravasation from mucosal postcapillary venules. RARs are excited by increases in interstitial liquid volume, so C-fibre receptors may indire ctly enhance cough via the RARs. (C) 1998 Elsevier Science B.V. All rights reserved.