Objective: To study the synthesis of inducible isoform of nitric oxide synthase (iNOS) in human nasal mucosal epithelial cells (HNMECs) under hypoxia, and the role of dexamethasone on this process.
Method: HNMECs were cultured without serum under normal condition and hypoxia for 3-48 hours, parts of them were cultured with dexamethasone. Cell cycle of epithelial cells was observed by flowcytometer. INOS mRNA was detected by in situ hybridization.
Result: Cell cycle of epithelial cells became long under hypoxia. iNOS mRNA expression increased with time dependence after hypoxia for 3 h compared with controls. The peak appeared after 12 h hypoxia (P < 0.01). Increased iNOS mRNA expressions were reduced significantly by dexamethasone, but higher doses of dexamethasone (> 4.0 g/L) did not result in further suppression.
Conclusion: Hypoxia can regulate expression of iNOS mRNA significantly in HNMECs, and dexamethasone can restrain this process significantly.