Effect of incubation in sodium chloride hypertonic solutions on Y-radiation and hydrogen peroxide induced DNA damage in human peripheral blood lymphocytes

Aim: to study the effect incubation in NaCI hypertonic solutions on the yield of DNA single-strand breaks (SSB) and alkali-labile sites (ALS) induced by y-radiation and hydrogen peroxide in human peripheral blood lymphocytes in vitro. Material and methods. The lymphocytes isolated from the peripheral blood of healthy women donors aged 21-26 years were used for the study. Cell irradiation at doses of 1, 2, 3 and 5 Gy was performed using the "AGAT P1" unit (Russia, y-radiation source — 60Co, a dose rate of 1 Gy/min) at 4°C. In case of hydrogen peroxide exposure (25, 50 and 100 uM) the cells were incubated for 15 minutes at 4°C. Analysis of the DNA SSB and ALS was performed using the alkaline DNA comet assay. Results. Incubation of cells in 0.35 M NaCI solution (non-histone proteins dissociation) increases the yield of DNA SSB and ALS induced by v-radiation and hydrogen peroxide at ~ 1.3 times. Increasing the NaCI concentration to 0.6 M (linker histone H1 dissociation) leading to almost double increase in the DNA damage yield (~ 1.7-1.8 times). Further increasing the NaCI concentration leading to disruption of the structure of nucleosomes (1.2 M) and almost complete chromatin deproteinization (2 M) increased the yield of DNA damage not such pronounced as expected (~ 2.2-fold at 2 M concentration). Conclusion. The results showed that incubation in NaCI hypertonic solutions significantly increases the sensitivity of lymphocytes to DNA damaging action of free radicals.