OBJECTIVETo explore the role of myeloperoxidase (MPO) and tumor necrosis factor-α (TNF-α) in myocardial injury induced by hind-limb ischemia-reperfusion (IR) in rats.

METHODSRat models of bilateral hindlimb IR established using a tourniquet were randomized into 9 groups, including a normal control group normal, 2 ischemic groups with hindlimb ischemia for 2 and 4 h, and 6 IR groups with a 4-h ischemia followed by reperfusion for 0.5, 2, 4, 6, 12, and 24 h. The plasma and myocardial levels of MPO and TNF-α in each group were measured, and the myocardial expression of TNF-α was determined with immunohistochemistry.

RESULTSCompared with the normal control group, the rats with a 2-h ischemia showed significantly increased levels of MPO and TNF-α in the plasma and myocardium. Compared with those in rats with a 4-h ischemia, the plasma and myocardial MPO levels increased significantly at 0.5 and 2 h of reperfusion, respectively; the plasma TNF-α level increased significantly at 4 h of reperfusion and myocardial TNF-α level decreased obviously at 12 h; plasma levels of MPO and TNF-α both significantly decreased at 24 h. The plasma MPO and TNF-α and myocardial TNF-α reached the peak levels at 4 h of reperfusion, and the peak myocardial MPO level occurred at 6 h. Immunohistochemistry showed that TNF-α positivity moderately increased after hindlimb ischemia, and further increased at 4 h of reperfusion but obviously reduced at 24 h.

CONCLUSIONThe activation of systemic and local neutrophils and inflammatory cytokines may play an important role in myocardial injury induced by hindlimb IR in rats.