The activities of lung stretch and irritant receptors during cough

In unilaterally vagotomized rabbits, changes in single vagal nerve fibers from the lung stretch and irritant receptors were studied during the cough reflex following ammonia vapour administered into the lungs. The discharge rates of slowly adapting pulmonary stretch receptors (SARs) before the onset of cough and at the onset of cough did not change significantly. In contrast, the occurrence of cough after ammonia inhalation was usually preceded by vigorous stimulation of the rapidly adapting pulmonary stretch receptors (RARs). These results suggest that the genesis of cough provoked by ammonia is mainly mediated by afferent input from RARs.