Abstract: Purpose : To study the effect of nit ric oxide (NO) in various concent rations on the nuclear DNA damage in esophageal carcinoma cells. Methods : Sodium nit roprusside (SNP) was used as the donor of NO invit ro , and EC109 esophageal carcinoma cell line as the cell model. The damage effect of NO was examined using the single cell gel elect rophoresis assay. Results : When SNP effected time periods were whether for 8h or 16h the SNP concent rations were increased at each time point , percentages of the comet tail of nuclei were higher and higher , their difference was significant byχ2 test ( P < 0. 01) . Regression analysis indicated that the percentage of the comet tail in the esophageal carcinoma nuclei was highly correlated to the SNP concent ration.Conclusion : The damage effect of NO on nuclear DNA depends on its concent ration in esophageal carcinoma cells.

Key words: nitric oxide, esophageal carcinoma cells, nuclear DNA damage, single cell gelelect rophoresis