RESUMO
BACKGROUND AND OBJECTIVES: Nitric oxide (NO) seems to have some potential to play a regulatory role in the airway function and it maybe related to the pathophysiology of several airway diseases. Although the pathophysiology of nasal polyp is poorly understood, a recent study has suggested that airway NO produced from paranasal sinus epithelium where mNOS is expressed constituitively without immunologic stimulation may play a critical role in the genesis of inflammatory nasal disease. MATERIALS AND METHODS: We examined the presence of mNOS and eNOS in the nasal cavity and paranasal sinus mucosa in 10 healthy persons of nasal septal deviation and 20 patients with nasal polyp by immunohistochemical staining using rabbit polyclonal anti- eNOS and anti-mNOS IgG. Relative quantification of eNOS and mNOS was done by RT-PCR. RESULTS: Immunoreactivity to eNOS and mNOS was positive in all nasal polyps and this reactivity was mainly restricted to the epithelial layer. Immunoreactivity to mNOS in the controls was negative for the inferior turbinate. RT-PCR showed more mNOS reactivity in the nasal polyp than in the control (p<0.03). CONCLUSION: These findings reinforce the concept that the epithelial layer is the main locus and mNOS may be one of the potential factors in the pathogenesis of nasal polyp.