. Author manuscript; available in PMC: 2011 Feb 1.

Published in final edited form as: Otolaryngol Clin North Am. 2010 Feb;43(1):15–vii. doi: 10.1016/j.otc.2009.11.012

Table 2.

Stimuli that do not initiate cough: Reflexes evoked, afferent nerves activated.

Stimulus	Reflexes evoked	Afferent nerves targeted
Bronchoconstriction ⁽¹⁾	mucus secretion, tachypnea	RARs
Esophageal acid	bronchospasm, mucus secretion	Esophageal nociceptors
Upper airway stimulation	Sneeze, mucus secretion	Trigeminal afferent nerves
Inc. airway luminal pressure	Respiratory slowing	SARs
Dec. airway luminal pressure	Tachypnea	RARs
Adenosine	Tachypnea, dyspnea	RARs, C-fibers
Pulmonary embolism	Tachypnea, dyspnea	RARs, C-fibers

⁽¹⁾

Bronchoconstrictors including histamine, methacholine, leukotriene D4, thromboxane A2 and neurokinin A fail to reliably evoke coughing in humans or in animals despite initiating reflex bronchospasm and mucus secretion, an increase in respiratory rate and dyspnea. Abbreviations: Inc.: Increase; Dec.: Decrease; RARs: Rapidly adapting receptors; SARs: slowly adapting receptors