Effects of ammonia on lung stretch receptor activity in the rabbit

The effects of ammonia on lung stretch receptor activity and respiration were studied in the rabbit. This chemical agent caused rapid and shallow breathings or augmented breaths or their combination. The majority of slowly adapting pulmonary stretch receptors (SRs) following ammonia inhalation increased their activity during both inspiration and expiration. At 30 s after ammonia inhalation, the responses of SR activity in both respiratory phases were grouped into four different types: an increase, no effect, a decrease, and no activity. In the time course of ammonia inhalation, the occurrence of a tonic firing pattern of SR activity preceded by a silent phase of the activity was observed in some SRs. In comparison with the findings of a previous report in the rabbit concerning the discharge pattern of SR activity after ammonia inhalation, the results obtained in this study suggest that some SRs in the rabbit are probably located peripheral to the site of the obstruction in the lung unit.