Figure 8. Lysosomal stability following exposure to DFO or a hydrated iron phosphate complex.

Cells were exposed for 12 h to 100 μM Zn. Some samples were then incubated for 3 h in normal medium containing 30 μM of an iron phosphate complex or 1 mM DFO. After another 1 h under standard culture conditions, the cells were exposed to a bolus dose of 100 μM H₂O₂ in PBS for 30 min, followed by another 6 h under standard culture conditions. Ensuing AO assay of preserved acidic vacuoles (late endosomes and lysosomes) by flow cytofluorimetry showed increased lysosomal stability in cells incubated with Zn or DFO, and reduced stability in those incubated with the iron phosphate complex. Results (percentage of cells with reduced number of intact lysosomes) are expressed as mean±S.D. and represent a minimum of four experiments. Comparisons were made with control cells exposed to H₂O₂ (second bar).