Abstract: Objective To investigate the effects of X-ray radiation on H9c2 cells and histone acetylation patterns, and to analyze the correlation between them. Methods H9c2 cells were randomly divided into control group and different model groups. The cells of model groups were irradiated with different doses of 2,4,6,8 Gy of X-ray radiation respectively. The activity of LDH in supernatants, the activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) in cells were detected by chromatometry. Cell apoptotic ratio was measured by annexin V-FITC/PI staining and flow cytometry analysis. Apoptosis-related protein Bcl-2,caspase-3 and histone acetylation related protein H3K9ac,HDAC3 were detected by Western blot. Results Compared with control group, the relative activity of LDH in supernatants and relative content of malondialdehyde (MDA) in H9c2 cells were increased (P＜0.05) in model groups, the relative activity of intracellular superoxide dismutase (SOD) was decreased(P＜0.05) in model groups. The apoptotic rate of H9c2 cells was increased in model groups compared with control group(P＜0.05). The protein expression of caspase-3 increased (P＜0.05), the expression of Bcl-2 decreased in model groups(P＜0.05), and also found that the protein expression of H3K9ac significantly decreased and the expression of HDAC3 significantly increased in model groups(P＜0.05). Conclusions X-ray radiation can induce H9c2 cells' injury and apoptosis,accompanied by the decrease of intracellular histone acetylation level, this change may be related to the increase of HDAC3 expression.

Key words: histone acetylation, radiation, cardiomyocyte