Salvianolate Reduces Murine Myocardial Ischemia and Reperfusion Injury via ERK1/2 Signaling Pathways in vivo

Objective: To analyze the effects of salvianolate on myocardial infarction in a murine in vivo model of ischemia and reperfusion (I/R) injury. Methods: Myocardial I/R injury model was constructed in mice by 30 min of coronary occlusion followed by 24 h of reperfusion and pretreated with salvianolate 30 min before I/R (SAL group). The SAL group was compared with SHAM (no I/R and no salvianolate), I/R (no salvianolate), and ischemia preconditioning (IPC) groups. Furthermore, an ERK1/2 inhibitor PD98059 (1 mg/kg), and a phosphatidylinositol-3-kinase (PI3-K) inhibitor, LY294002 (7.5 mg/kg), were administered intraperitoneal injection (i.p) for 30 min prior to salvianolate, followed by I/R surgery in LY and PD groups. By using a double staining method, the ratio of the infarct size (IS) to left ventricle (LV) and of risk region (RR) to LV were compared among the groups. Correlations between IS and RR were analyzed. Western-blot was used to detect the extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (AKT) phosphorylation changes. Results: There were no significant differences between RR to LV ratio among the SHAM, I/R, IPC and SAL groups (P > 0.05). The SAL and IPC groups had IS of 26.1%+/- 1.4% and 22.3%+/- 2.9% of RR, respectively, both of which were significantly smaller than the I/R group (38.5%+/- 2.9% of RR, P < 0.05, P < 0.01, respectively). Moreover, the phosphorylation of ERK1/2 was increased in SAL group (P < 0.05), while AKT had no significant change. LY294002 further reduced IS, whereas the protective role of salvianolate could be attenuated by PD98059, which increased the IS. Additionally, the IS was not linearly related to the RR (r=0.23, 0.45, 0.62, 0.17, and 0.52 in the SHAM, I/R, SAL, LY and PD groups, respectively). Conclusion: Salvianolate could reduce myocardial I/R injury in mice in vivo, which involves an ERK1/2 pathway, but not a PI3-K signaling pathway.