2.7. Mouse model of cardiac ischemia/reperfusion (I/R) injury

Myocardial I/R injury was induced by ligation of left anterior descending coronary artery (LAD) for 30 minutes and reperfusion for 24 hours as previously described (Li et al., 2017). Briefly, mice were anesthetized by intraperitoneal injection of ketamine (120 mg/kg) and xylazine (4 mg/kg), intubated and ventilated with pure O₂, using a MiniVent mouse ventilator (Model 845, Harvard Apparatus). Body temperature was kept at 35–36 °C with a temperature-controlled surgical table. After a left thoracotomy was performed through the fifth intercostal space, the LAD was ligated with a 6-0 silk suture for 30 minutes of ischemia. At the end of ischemia period, reperfusion was accomplished by releasing the slipknot and the chest was closed in layers. After 24 hours of reperfusion, transthoracic echocardiography was performed, and the mice were sacrificed for infarct size measurement. In sham-operated mice, the silk suture placed underneath the LAD artery was not ligated. Four hours after gavage of vehicle, NR, NR + RES or NR/RESms, the mice were randomly assigned to the Sham, I/R + Vehicle, I/R + NR, I/R + NR + RES and I/R + NR/RESms groups.