Effect of L-NAME and apocynin on ROS production induced by high-glucose treatment in HCAECs. HCAECs were exposed to high glucose (35.6 mM) for 24 h, and L-NAME (300 µM) or apocynin (100 µM) for the same period. Representative images show DCF fluorescence in control (A, E), high-glucose treatment (B, F) and high-glucose + L-NAME (C) or + apocynin (G). High-glucose treatment increased ROS production, which was prevented by L-NAME (D) or apocynin (H). *p < 0.05 vs control, #p < 0.05 vs high-glucose (20 cells/dish from 2-3 dishes). Scale bar = 100 µm.