OBJECTIVETo investigate whether adiponectin plays a role in the protection of myocardium in the rat myocardial ischemia preconditioning (IPC) model.

METHODInfarct 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.

RESULTInfarct 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).

CONCLUSIONIPC 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.