Previous studies demonstrated the effect of Trimetazidine (TMZ) on alleviating cardiomyocytes Hypoxia/Reoxygenation (H/R) injuries and the protective effect of autophagy on Ischemia-Reperfusion (I/R) cell injuries. However, whether the protection mechanism of TMZ was also involved in autophagy remained unclear. Our study introduces the role of HMGB1 to examine the regulation of TMZ on autophagy against cardiomyocytes H/R injuries. After cell extraction and identification through anti-α-actin staining, the cardiomyocytes were made hypoxic and reoxygenated, each for 3 h, and then treated with various concentrations of TMZ and transfected with siHMGB1. Cell viability and apoptosis were measured by the MTS method and flow cytometry, respectively. The expressions of autophagy-related factors (LC3-I, LC3-II, Beclin-1) and HMGB1 were detected by Western blot and qPCR. Lactate dehydrogenase (LDH) release was assessed by ELISA kit. The cardiomyocytes were extracted. H/R decreased the cell viability and increased the LDH level and apoptosis of cardiomyocytes. TMZ had no effect on untreated cardiomyocytes, but it reversed the adverse impact of H/R on cardiomyocytes. The expressions of LC3-II, Beclin-1, and HMGB1 and the ratio of LC3-II/LC3-I were increased in H/R-processed cardiomyocytes and further raised by TMZ pretreatment. However, siHMGB1 transfection aggravated the impact of H/R on cardiomyocytes and suppressed the protective effects of TMZ on H/R damaged cardiomyocytes by increasing the LDH level and apoptosis and reducing the viability of cardiomyocytes. Autophagy was inhibited by siHMGB1 in TMZ-pretreated and H/R-processed cardiomyocytes. TMZ protected cardiomyocytes against H/R injuries may through regulating HMGB1 to increase the impact of autophagy.

中文翻译：

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曲美他嗪通过上调HMGB1表达促进自噬减轻缺氧/复氧诱导的新生小鼠心肌细胞凋亡

先前的研究证明了曲美他​​嗪 (TMZ) 对减轻心肌细胞缺氧/复氧 (H/R) 损伤的作用以及自噬对缺血再灌注 (I/R) 细胞损伤的保护作用。然而，TMZ的保护机制是否也参与自噬尚不清楚。我们的研究介绍了 HMGB1 在检查 TMZ 对心肌细胞 H/R 损伤自噬的调节作用。细胞提取和抗α-肌动蛋白染色鉴定后，使心肌细胞缺氧和复氧，每次3小时，然后用不同浓度的TMZ处理并转染siHMGB1。分别通过MTS方法和流式细胞术测量细胞活力和细胞凋亡。自噬相关因子（LC3-I、LC3-II、Beclin-1) 和 HMGB1 通过蛋白质印迹和 qPCR 检测。通过ELISA试剂盒评估乳酸脱氢酶(LDH)释放。提取心肌细胞。H/R降低细胞活力，增加心肌细胞的LDH水平和凋亡。TMZ 对未经处理的心肌细胞没有影响，但它逆转了 H/R 对心肌细胞的不利影响。LC3-II、Beclin-1 和 HMGB1 的表达以及 LC3-II/LC3-I 的比率在 H/R 处理的心肌细胞中增加，并通过 TMZ 预处理进一步提高。然而，siHMGB1转染加重了H/R对心肌细胞的影响，并通过增加LDH水平和凋亡以及降低心肌细胞活力来抑制TMZ对H/R损伤心肌细胞的保护作用。自噬在 TMZ 预处理和 H/R 处理的心肌细胞中被 siHMGB1 抑制。