2.3. Experimental Design

The I/R injury animal model was established by the left anterior descending (LAD) coronary artery ligation for 30 min followed by 1 h reperfusion. Briefly, after being anesthetized with a 30 mg/kg pentobarbital sodium intraperitoneally, rats were ventilated with a positive pressure respirator at a stroke volume of 12 mL/kg and a rate of 60 strokes per minute with 95% O₂ and 5% CO₂ throughout the experiment. The rat heart was exposed through a left thoracotomy. Then, the LAD was ligated 2-3 mm from its origin and loosened to simulate I/R rat model (ischemia for 30 min and reperfusion for 1 h). Rats were randomly apportioned in equal animals (n = 10) to five experimental groups: (1) sham group: rats were subjected to the entire surgical procedure but without the induction of I/R; (2) model group: I/R injury animal model was constructed by LAD ligation for 30 min, and then the LAD was allowed 1 h reperfusion; and (3) three genistin-treated groups: different doses (20, 40, and 60 mg/kg body weight, resp.) of genistin dissolved in 0.5% sodium carboxyl methyl cellulose (CMC-Na) solution were given intragastrically for 5 days before operation.