Yangxinshi tablet protects against myocardial injury and increases skeletal muscle exercise capacity by regulating mitochondrial bioenergetics

Yangxinshi tablet (YXST), as the traditional Chinese medicine, could significantly improve cardiac function and exercise tolerance in patients with coronary heart disease. However, molecular mechanisms of YXST protecting against myocardial injury and promoting skeletal muscle exercise capacity is still unclear. This study aimed to clarify the efficacy and potential mechanisms of YXST in myocardial injury and skeletal muscle exercise capacity. Mice were randomly divided into 6 groups (n = 10-20 every group) and administrated for 6 weeks: control group, myocardial ischemia‒reperfusion group (I/R group), YXST group (I/R mice treated with YXST, respectively 250,500 and 1000 mg/kg/day) and I/R treated with trimetazidine (TMZ) group (20 mg/kg/day). Meanwhile, the mice were divided into 4 groups (n = 8-9 every group), which were control group, YXST group (250, 500 and 1000 mg/kg/day for 6 weeks). Cardiac function, exercise tolerance, grip strength, skeletal muscle structure and myoblasts proliferation were detected. RNA-sequence assays and mass spectrometry analysis of C2C12 myotubes were performed and analyzed. UHPLC was employed to detect YXST's characterize and its principal components. The target protein of YXST were assessed by molecular docking methods. Mitochondria oxygen consumption rate was detected by Seahorse. YXST improved cardiac function and exercise tolerance, enhanced the slow type I fibers expression, ameliorated mitochondrial biogenesis, and attenuated inflammation level under I/R condition in vivo. YSXT could directly promote exercise capacity and satellite cells proliferation of skeletal muscle under normal condition in vivo. We also found that YXST promoted C2C12 myoblasts differentiation and myotubes formation by regulating mitochondrial biogenesis, mitophagy, and oxidative phosphorylation in vitro. Molecular docking analysis demonstrated that the top 9 compounds identified in blood may bind with BTB and CNC homology 1 protein (BACH1). CETSA assay revealed that YXST had a significantly effect on increasing the thermal stability of BACH1 protein. Interestingly, YXST stimulated the secretion of cardioprotective myokines. This study revealed that YXST improved cardiac function and exercise tolerance in I/R mice, particularly we found that YXST could directly enhance the exercise capacity of mice under normal condition. Mechanismly, YXST significantly regulated mitochondrial biogenesis, oxidative phosphorylation and myokine production in vivo and in vitro. Our findings provide novel mechanistic insights and pharmacological basis for the application of YXST against coronary heart disease and skeletal muscle injury.