Yangxinkang tablet protects against cardiac dysfunction and remodelling after myocardial infarction in rats through inhibition of AMPK/mTOR-mediated autophagy

Context Acute myocardial infarction (AMI) is defined as myocardial necrosis. Clinicians use the traditional Chinese patent medicine Yangxinkang Tablet (YXK) to treat chronic heart failure. Objective To explore the effects of YXK on heart injury following AMI and the underlying mechanisms. Materials and methods The AMI model was produced in Wistar rats by permanent ligation of the left anterior descending coronary artery. Rats were divided into the following five groups: Sham (n = 6), MI (Model, n = 10), AICAR (AMPK agonist, 50 mg/kg/d, i.p., n = 10), Compound C (AMPK inhibitor, 10 mg/kg/d, i.p., n = 10), and YXK (0.72 g/kg/d, gavage, n = 10) groups. Cardiac function, cardiac fibrosis, apoptosis, and expression of p-AMPK, p-mTOR, and autophagy-related proteins was measured after 4 weeks of treatment after the successful modelling of the AMI. Results Compared to MI group, both YXK and AMPK inhibitor improved cardiac dysfunction and reduced cardiac fibrosis (15.6 ± 2.3; 22.6 ± 4.6 vs. 34.6 ± 4.3%) and myocardial cell apoptosis (12 ± 3.67; 25.6 ± 6.8 vs. 54 ± 4.8%). Futhermore, YXK and AMPK inhibitor significantly decreased p-AMPK expression by 11.05% and 14.64%, LC3II/I by 25.08% and 35.28% and Beclin-1 by 66.71% and 33.85%, increased p-mTOR by 22.14% and 47.46% and p62 by 70.83% and 18.58%. Conclusions The underlying mechanism appears to include suppression of autophagy via inhibiting AMPK/mTOR signalling, suggesting that YXK may serve as a potentially effective Chinese herbal compound for suppressing cardiac fibrosis in heart injury.