Zishenhuoxue Decoction-induced Myocardial Protection Against Ischemic Injury Through TMBIM6-VDAC1-mediated Regulation of Calcium Homeostasis and Mitochondrial Quality Surveillance

Background: Zishenhuoxue decoction (ZSHX), a Chinese herbal medicine, exhibits myocardial and vascular endothelial protective properties. The intricate regulatory mechanisms underlying myocardial ischemic injury and its association with dysfunctional mitochondrial quality surveillance (MQS) remain elusive.

Hypothesis/purpose: To study the protective effect of ZSHX on ischemic myocardial injury in mice using a TMBIM6 gene-modified animal model and mitochondrial quality control-related experiments.

Study Design: Using model animals and myocardial infarction surgery-induced ischemic myocardial injury TMBIM6 gene-modified mouse models, the pharmacological activity of ZSHX in inhibiting ischemic myocardial injury and mitochondrial homeostasis disorder in vivo was tested.

Methods: Our focal point entailed scrutinizing the impact of ZSHX on ischemic myocardial impairment through the prism of TMBIM6. This endeavor was undertaken utilizing mice characterized by heart-specific TMBIM6 knockout (TMBIM6) and their counterparts, the TMBIM6 transgenic (TMBIM6) and VDAC1 transgenic (VDAC1) mice.

Results: ZSHX demonstrated dose-dependent effectiveness in mitigating ischemic myocardial injury and enhancing mitochondrial integrity. TMBIM6 hindered ZSHX's cardio-therapeutic and mitochondrial protective effects, while ZSHX's benefits persisted in TMBIM6 mice. TMBIM6 also blocked ZSHX's regulation of mitochondrial function in HR-treated cardiomyocytes. Hypoxia disrupted the MQS in cardiomyocytes, including calcium overload, excessive fission, mitophagy issues, and disrupted biosynthesis. ZSHX counteracted these effects, thereby normalizing MQS and inhibiting calcium overload and cardiomyocyte necroptosis. Our results also showed that hypoxia-induced TMBIM6 blockade resulted in the over-activation of VDAC1, a major mitochondrial calcium uptake pathway, while ZSHX could increase the expression of TMBIM6 and inhibit VDAC1-mediated calcium overload and MQS abnormalities.

Conclusions: Our findings suggest that ZSHX regulates mitochondrial calcium homeostasis and MQS abnormalities through a TMBIM6-VDAC1 interaction mechanism, which helps to treat ischemic myocardial injury and provides myocardial protection. This study also offers insights for the clinical translation and application of mitochondrial-targeted drugs in cardiomyocytess.