Forty-two SD rats were randomly divided into sham operation group (n = 6) and I/R model group (n = 36). In the model group, rats were ligated with left anterior descending coronary artery to simulate MI. Specifically, after anesthetizing the animals in the I/R model group, an oblique incision was made in the third and fourth intercostal spaces of the left chest to expose the heart. Under a stereomicroscope, the junction of the pulmonary artery cone and the left atrial appendage was ligated with 6/0 noninvasive suture needle silk threads at 1-2 mm below the starting point of the coronary artery. Successful ischemia was indicated by ST segment elevation or T wave height and peaks of MI performance on electrocardiogram (ECG). The ligation was stopped after 45 minutes of ischemia, and the rats were maintained for 24 hours after reperfusion. As a drug treatment, 6 I/R model rats were treated with 20 nmol miRNA NC inhibitor (Thermo Fisher Scientific, Waltham, MA), 20 nmol miR-375-3p antagomir (Thermo Fisher Scientific, Waltham, MA) and 2 mg/kg Ferrostatin-1 (Fer-1; MCE, USA) for 28 days. The myocardial tissues of rats in the sham operation and I/R model groups as well as I/R model drug treatment group were then used for subsequent testing.