DEX pretreatment significantly attenuated I/R-induced cardiac damage, as evidenced by decreases in short-term injury indicators including myocardial infarct size, cTnI release, myocardial apoptosis, cardiac HMGB1 expression, IL-6 and TNF-α production, as well as improvement on long-term cardiac function at 4 weeks post-reperfusion. This evidence concerns the gene HMGB1 and myocardial infarction.