RESUMEN
Objective To study the co-effects of methylene blue(MB) and exposure with the cold light source on cell DNA damage, and to explore the mechanism involved. Methods The alkaline single cell gel electrophoresis was used to determine cell DNA damage. Apoptosis of the cells was determined by flow cytometry analysis using Annexin V-FITC/PI staining. DCFH-DA probe was used to determine endocellular Reactive Oxygen Species (ROS). Results The levels of DNA damage in the SGC7901 adenocarcinoma cells treated with methylene blue in the light were significantly increased compared to that of control ( F = 8.39, P＜0.05 ). The DNA damage levels were related to the length of time of light exposure, and the damage was recovered to a certain level after light withdrew. Cell apoptosis ( x2=7.71,P ＜0.05)and endocellular ROS level (F = 34.11, P＜0.01＝ increased significantly in the exposure group. Conclusions Methylene blue chromoendoscopy can induce DNA damage and cell apoptosis, and the mechanism may be associated with ROS produced by the photochemical reaction.