Salvianolic acid B alleviates myocardial ischemic injury by promoting mitophagy and inhibiting activation of the NLRP3 inflammasome

Ischemic heart disease is a major cause of mortality and disability worldwide. Salvianolic acid B (Sal B) is one of the main water-soluble components of Salvia miltiorrhiza Bge. Numerous studies have demonstrated that Sal B could exert significant anti-inflammatory and cardiovascular protective effects; however, the underlying mechanisms remain unclear. To elucidate the association between myocardial ischemia and inflammation, and to develop effective protective drugs, a rat model of myocardial ischemia was induced using isoproterenol (ISO) and an inflammation model in H9C2 cells was induced with lipopolysaccharide + adenosine triphosphate. Both of these models were treated with different concentrations of Sal B (5, 10 and 15 mg/kg in vivo; 1, 5 and 25 µM in vitro). In vivo, the serum levels of creatine kinase isoenzyme MB, glutamic oxaloacetic transaminase and IL-1β, the cardiac function and the mRNA expression levels of NLR family pyrin domain-containing 3 (NLRP3) inflammasome components were evaluated using ELISAs, an electrocardiogram, hematoxylin and eosin staining and reverse transcription-quantitative PCR, respectively. The results demonstrated that treatment with Sal B markedly alleviated the acute myocardial ischemic injury induced by hypodermic injection of ISO in rats. In vitro, the results of reactive oxygen species (ROS) detection, JC-1 staining, western blotting and TUNEL assays showed that Sal B treatment significantly inhibited intracellular ROS production, increased the mitochondrial membrane potential, regulated the expression of mitophagy-related proteins, inhibited the activation of the NLRP3 inflammasome and inhibited apoptosis in H9C2 cells. In conclusion, these findings indicated that Sal B exerted protective effects against myocardial ischemic injury by promoting mitophagy and maintaining mitochondrial function.