Xing Zhou,1,* Quan Lu,2,* Qiu Wang,2,* Wenxin Chu,2 Jianhao Huang,2 Jinming Yu,2 Yuechou Nong,2 Wensheng Lu2,* 

1Pharmacy Department, Guangxi Academy of Medical Sciences and the People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, People’s Republic of China; 2Department of Endocrinology and Metabolism, National Key Endocrine Clinical Construction Specialty, Guangxi Academy of Medical Sciences and the People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Wensheng Lu; Yuechou Nong, Department of Endocrinology and Metabolism, National Key Endocrine Clinical Construction Specialty, Guangxi Academy of Medical Sciences and the People’s Hospital of Guangxi Zhuang Autonomous Region, No. 6, Taoyuan Road, Nanning, Guangxi, 530021, People’s Republic of China, Email Lwswxqz@163.com; wslu@gxams.org.cn; yuechou_gx@163.com

Background: Mitochondrial calcium uptake-induced mitophagy may play an essential role in myocardial ischemia/reperfusion (MI/R) injury. Diltiazem hydrochloride (DIL), a traditional calcium channel blocker, can alleviate MI/R injury by blocking calcium overload. However, whether the protective mechanism of DIL involves mitophagy remains elusive. This study aimed to clarify the underlying molecular mechanism by which DIL ameliorates MI/R injury by downregulating mitophagy in vivo and in vitro.
Methods: Thirty rats were randomized into three groups: the sham, MI/R, and MI/R+DIL (1 mg/kg) groups (n = 10/per group). MI/R injury was induced by ligating the left anterior descending (LAD) artery for 30 min followed by 60 min of reperfusion in vivo. H9C2 cells were selected to establish an oxygen-glucose deprivation/recovery (OGD/R) model to simulate MI/R injury in vitro. The potential mechanism by which DIL alleviates MI/R injury was analyzed based on tissue morphology, mitophagy-related gene transcription, and protein expression.
Results: According to histological and immunohistochemical evaluations, DIL significantly alleviated myocardial damage in vivo. Moreover, DIL significantly increased cell viability, attenuated OGD/R-induced apoptosis, and inhibited mitochondrial autophagy in vitro. Mechanistically, DIL attenuated mitochondrial autophagy through the upregulation of dual-specificity protein phosphatase 1 (DUSP1) and the downregulation of c-Jun N-terminal kinase (JNK) and Bcl2 interacting protein 3-like (BNIP3L, also known as NIX) expression.
Conclusion: Diltiazem hydrochloride protects against myocardial ischemia/reperfusion injury in a BNIP3L/NIX-mediated mitophagy manner in vivo and in vitro.

Keywords: diltiazem hydrochloride, calcium channel blockers, myocardial infarction, myocardial ischemia/reperfusion injury, mitophagy