AIM: To study the effect of different concentration of Verapamil(Ver)on Ca²⁺ of guinea pig retinal pigment epithelial(RPE)cells in vitro and compare the changes of Ca²⁺ with or without Ver under different forms of light.

METHODS: Ten two-week-old healthy guinea pigs were chosen and RPE cells were cultured in vitro. Cells were divided into Ver treated and untreated groups, then each group further divided into 4 groups: focused light group, defocused light group, parallel light group and control group. The first three groups were exposed to the focused light, defocused light(2 forms of light were transformed from parallel light by passing through different lens)and the parallel light respectively, and control group was removed from exposure of light. After exposed to different forms of light, the fluorescence intensity of intracellular Ca²⁺ were detected by laser scanning confocal microscope(LSCM)immediately. Cool white light was used as light source. Cells were exposed to light with same spot diameter and degree of irradiation level(at 300 LUX)for 30 minutes respectively. Horizontal temperature of cells changed between 36.5℃-37.2℃. There was no natural light interference. In order to avoid the impaction of refraction of liquid, most of the medium were siphoned off before irradiation. The data were analysed by SPSS 13.0 statistical software, completely randomized design ANOVA and Pearson linear correlation analysis were used as statistical methods. The forms-effect relations were explored.

RESULTS: Treated with Ver for 12 hours, the apoptosis rates of RPE cells in 20, 40, 80mg/L concentration group had no significant difference compared with control group(P>0.05). Ver could reduce the Ca²⁺ fluorescence intensity of RPE cell,and there was significantly statistical difference in 80mg/L group(P<0.05). The Ca²⁺ fluorescence intensity of focused group of no Ver treated part was significantly higher than other groups, had significant differences compared with the other groups(P<0.05). After added 80mg/L Ver on the RPE cells for 12 hours, exposure to light did not significantly increase the Ca²⁺ fluorescence intensity, there was no significant difference among the 4 groups(P >0.05).

CONCLUSION: Focused light can significantly stimulate the concentration of intracellular Ca²⁺ of RPE cells. Ver above a certain concentration can induce apoptosis of RPE cells; 80mg/L Ver can effectively reduce intracellular Ca²⁺ fluorescence intensity under the premise of not leading to apoptosis of RPE cells. Different forms of light have no effect on the Ca²⁺ fluorescence intensity of RPE cells after treated with Ver(80mg/L)for 12 hours.