LAUSR

Background: Suxiao Jiuxin Pill (SX), Chinese traditional medicine primarily consisting of tetramethylpyrazine and borneol, has been shown to protect against ischemic heart diseases. Nevertheless, the involved mechanism still remains unclear. The following study aimed to investigate the potential protective effect and molecular mechanisms of SX on apoptosis in HL‐1 cardiomyocytes. Methods: Simulated hypoxia was established by culturing HL‐1 cardiomyocytes in DMEM with no glucose or serum in a hypoxic chamber with 95% N2 and 5% CO2 for 24 h. HL‐1 cardiomyocytes were divided into 5 groups: control, hypoxic injury, hypoxic injury + insulin (PI3K agonist, 10 &mgr;M), hypoxic injury + SX (100 &mgr;g/mL), and hypoxic injury + SX + LY294002 (PI3K inhibitor, 10 &mgr;M) (n = 3 wells/group). The anti‐apoptotic effect of SX was evaluated by Annexin V/PI analysis. Mitochondrial membrane potential (&Dgr;ψ) was detected by JC‐1 assay. The protein expression of PI3K, phosphorylated PI3K (p‐PI3K), Akt, phosphorylated Akt (p‐Akt), GSK3&bgr; and phosphorylated GSK3&bgr; (p‐GSK3&bgr;) were detected by western blot. Results: SX exhibited anti‐apoptotic effect in HL‐1 cardiomyocytes; nonetheless, the effect was blocked by PI3K inhibitor LY294002. Also, the anti‐apoptotic effect of SX was mediated by increased mitochondrial membrane potential (&Dgr;ψ). Furthermore, p‐PI3K, p‐Akt, and p‐GSK3&bgr; expressions were significantly increased after SX treatment, while they were all reduced after administration of LY294002. Conclusion: SX protects HL‐1 cardiomyocytes from apoptosis induced by hypoxia, partly through enhancing the phosphorylation of PI3K/Akt/GSK3&bgr; signaling pathway.