Ischemia preconditioning attenuated myocardial ischemia via upregulating the expression of adiponectin in rat

OBJECTIVE: To investigate whether adiponectin plays a role in the protection of myocardium in the rat myocardial ischemia preconditioning (IPC) model. METHOD: Infarct size was measured by Masson's Trichrome staining, the expression of protein and mRNA of adiponectin at 0, 6, 12 and 24 h after IPC was examined by immunohistochemistry and quantitative real time RT-PCR, plasma levels of adiponectin at above mentioned four time points after IPC were detected by ELISA in IPC and MI rats. RESULT: Infarct size was smaller in IPC than in MI rats (20% ± 2% vs. 31% ± 3%, P < 0.05). The expression of adiponectin mRNA at 6 h and 12 h after IPC was 2.2 and 2.1 times higher than in Sham rats at respective time points (P < 0.05). Immunohistochemistry staining evidenced increased adiponectin expression in the ischemic area and weak expression of adiponectin in non-ischemic area (P < 0.05). Compared to the sham group, the plasma level of adiponectin increased significantly at 0, 6 and 12 h after IPC (0 h: 7.40 ± 0.47 vs. 10.90 ± 1.74; 6 h: 8.18 ± 1.41 vs. 10.98 ± 1.74; 12 h: 6.97 ± 1.02 vs. 9.31 ± 0.96, P < 0.05). CONCLUSION: IPC reduced infarction size, upregulated the myocardial expression of adiponectin at mRNA and protein levels, and increased plasma adiponectin concentration, suggesting that the adiponectin may play a critical role in the protective effect of IPC.