The morphological basis for the effect of substance P on mucociliary activity in rabbit maxillary sinus

The mucociliary (m.c.) activity in rabbit maxillary sinus is accelerated by the neuropeptide substance P (SP). The morphological basis for this mechanism was investigated by immunocytochemistry using monoclonal antibodies directed against SP. SP-like immunoreactivity was found in nerve fibres in the subepithelial layer of the sinus mucosa, in the maxillary nerve, and in nerve endings close to nerve cell bodies in the sphenopalatine ganglion. Thus, there is morphological evidence in the rabbit that SP plays a role in the regulation of m.c. activity. The results also support the view that the rabbit maxillary sinus is a suitable experimental model for studying SP effects in the airway mucosa.