Fig. 2

Kinetics of NO production in culture supernatant of PK-15 cells. When 80% confluent monolayers formed, NAP, SNP, VC and SNP plus VC were added into 96-well cell culture plates, four wells for each treatment, and nontreated cells served as the control. Supernatant from each sample was collected at different time points, then NO levels were quantitated by Griess reaction with a microplate reader at 540 nm and compared to a standard curve made from sodium nitrite. Data were presented as means ± SD from three independent experiments (**P < 0.01 vs the untreated control group, #P < 0.05 vs SNP-treated group)