Fig. 2. Primary human bronchial epithelial (HBE) cells converted NO to Nitrite and Nitrate.

NO donor was incubated with and the other without HBE cells. The cells were cultured on human placental collagen-coated Costar Transwell filters with complete DMEM/F-12 growth medium for 24 hrs. Prior to treat the cells with DETA NONOate (50 µM), the cells were washed twice with PBS and the culture medium was replaced with serum deprived DMEM/F-12 medium. Cells were then placed in a regular CO₂ incubator (21% O₂, 5% CO₂) or hypoxic chamber (1% O₂, 5% CO₂) for 24 hrs after adding DETA NONOate (50 µM). Nitrite (top panel) and nitrate (bottom panel) levels in conditioned media were then measured (see Materials and Methods).