Protective effect of glycyrrhizin on infarct size in rats with myocardial I/R injury. Sprague-Dawley rats were divided into five groups: Sham, NS and myocardial I/R injury + pre-treatment with 2, 4 and 10 mg/kg glycyrrhizin groups, respectively, to investigate the effect of glycyrrhizin on infarct size in myocardial I/R injury. Data are presented as the mean ± standard deviation. ##P<0.01 vs. NS. I/R, ischemia/reperfusion; Sham, sham-treated group; NS, myocardial I/R injury + non-treated group; 2 mg/kg, myocardial I/R injury + pre-treatment with 2 mg/kg glycyrrhizin group; 4 mg/kg, myocardial I/R injury + pre-treatment with 4 mg/kg glycyrrhizin group; 10 mg/kg, myocardial I/R injury + pre-treatment with 10 mg/kg glycyrrhizin group.