Figure 5. Dose-dependent H₂O₂-induced toxicity in individual ARPE-19 cells shown by time-dependent image analysis of nuclear propidium iodide (PI) fluorescence. Live cell imaging of dynamic changes in nuclear PI fluorescence in ARPE-19 cells containing control particles (latex beads) after treatment with three doses of H₂O₂ delivered either as A: a pulse or B: generated enzymatically after the addition of glucose oxidase (GOx) The concentrations of H₂O₂ (in μM) or GOx (in mU/ml) are indicated. Numbers of cells selected for analysis were as follows. A: 900 μM, n=166; 1000 μM, n=194; 1200 μM, n=163. B: 17 mU/ml, n=123; 22.5 mU/ml n=123; 30 mU/ml, n=165. Data are from representative experiments and are the percent of cells pre-selected for bead content that survived (no nuclear PI) with time. All curves within each treatment protocol differ significantly from one another (GraphPad Prism 5 survival analysis, p<0.02). C: Bright-field-fluorescence overlays of cultures treated with 22.5 mU/ml GOx to illustrate the time-dependent increase in numbers of cells exhibiting nuclear PI fluorescence (shown white). Images were captured at 5 min intervals; the acquisition times of the selected images are indicated. Scale bar: 20 μm.