Salvianolate protects H9c2 cells from hypoxia/reoxygenation injury-induced apoptosis by attenuating mitochondrial DNA oxidative damage

Abstract

Objective: To investigate the possible mechanism related to the protective effects of salvianolate in H9c2 cells underwent hypoxia/reoxygenation (H/R)-injury. Methods: H9c2 cells were divided into four groups: control group, salvianolate group (S group), H/R group, and salvianolate+ H/R group(S+ H/R group), in which the H9c2 cells were pretreated with salvianolate before H/R-treatment.Apoptotic cells were detected by Tunel assays and AnnexinⅤ-FITC apoptosis detection kit.The intracellular ATP level, the change of mitochondrial membrane potential and the mitochondrial DNA oxidative damage were also determined in these groups. Results: (1) The apoptosis rate of H/R group(26.36±5.14)% was significantly higher compared to control group(2.71±1.66)%(P=0.000 4), which could be significantly reduced in S+ H/R group(17.28±4.75)%(P=0.012 8 vs. H/R group , P=0.003 9 vs. control group). The ratio of AnnexinⅤ and PI double positive cells in H/R group(28.23±6.73)% was significantly higher compared to control group(3.53±2.83)%(P=0.001 1), which was significantly reduced in S+ H/R group(18.10±4.56)%(P=0.037 2 vs. H/R group, P=0.038 3 vs. control group). (2)The ATP level of H9c2 cells in H/R group(49.05±10.12)% was significantly lower than in control group 100%(P=0.000 5), which was significantly increased in S+ H/R group(68.67±13.32)%(P=0.019 9 vs. H/R group). Confocal microscope showed that red fluorescence was dominant in the control group, red fluorescence was significantly reduced, while green fluorescence was significantly increased in H9c2 cells of H/R group and the fluorescence ratio of red to green in H/R group((37.13±8.47)%) was significantly decreased compared to control group (100%, P=0.000 1), fluorescence ratio of red to green was significantly increased in S+ H/R group((63.77±12.32)% vs. H/R group, P=0.007 3). (3)The mitochondrial DNA oxidative damage in different groups: there was only few 8-hydroxyguanine (8-OHdG) expression, which marked as green, in control group, and 8-OHdG expression was significantly upregulated in H/R group, moreover, the 8-OHdG was co-localized with mitochondria.The expression of 8-OHdG was significantly lower in S+ H/R group compared to H/R group. Conclusion: Salvianolate can reduce mitochondrial DNA oxidative damage, and protect mitochondrial function, thus inhibit myocardial cell apoptosis and eventually reduce the myocardial H/R-injury in H9c2 cells.