Figure 5. Light exposure causes massive calcium influx in RGC-5 cells. A-D: Calcium influx was detected with fura-2 with an inverted fluorescence microscope. A, B: Control; C, D: Cells treated with 2,600 lx light for 2 days; Scale bar=30 μm. E: Expanded overlay of typical responses was determined with calcium indicator. RGC-5 cells were cultured under the 2,600 lx light or with no light for 2 or 3 days. The intracellular free calcium concentration was measured using the fura-2/AM methodology. [Ca²⁺]i was significantly increased by light exposure, as indicated by the green fluorescence. F: RGC-5 cells were pre-cultured in normal media containing cobalt (50–200 μmol/l) and then exposed to 2,600 lx light for 3 days. Cell viability was determined with the MTT assay. Pre-treatment with 50–200 μmol/l cobalt significantly increased cell viability after light exposure. The results are expressed as a percentage of the control cells and are mean values±SEM (n=48, three separate cultures). (p<0.001, one-way ANOVA and Bonferroni test).