Figure 4.

Measurement of low levels of ROS in PMA-stimulated HT-29 cells using the new chemiluminescent imaging method. (a) HT-29 cells (2 × 10⁵) were incubated in HBSS and stimulated with PMA (200 nM) for the indicated times. Chemiluminescence was assessed using the imaging system. (b) HT-29 cells were incubated in Opti-MEM and stimulated with PMA (200 nM) for the indicated times. Conditioned media was then used to measure extracellular ROS. HT-29 cells were pretreated with (c) NAC (10 mM) or (d) DPI (10 μM) for 1 h prior to stimulation with PMA (200 nM) for 30 min. ROS concentration was calculated using a H₂O₂ standard curve (n = 3, ±SD). ^∗ p < 0.01 and ^∗∗ p < 0.001 vs. control.