Objective:To establish the myocardial ischemia-reperfusion injury (MIRI) model by ligation of the left ventricular branch of coronary artery in rabbits.Methods:Totally 36 New Zealand white rabbits were randomly divided into 3 groups according to the random number table method, including the sham group ( n=6), the model group ( n=15), and the sustained ischemia group ( n=15). The rabbits were placed under general anesthesia, then endotracheal intubation and common carotid artery intubation were performed. The intercostal muscle between the 3rd and 4th ribs of the left thorax was divided with the aid of a ventilator. The left ventricular branch was located and processed according to the different groups. After successful modeling, the gross morphological change of the heart was observed by naked eye, and the survival rate and modeling success rate of rabbits in each group were calculated respectively. Record the waveform of limb lead Ⅱ electrocardiogram before left ventricular branch ligation (N), 45 minutes of ischemia (I45), 15 minutes of reperfusion (R15), 30 minutes of reperfusion (R30), and 60 minutes of reperfusion (R60). Serum cardiac troponin Ⅰ (cTnⅠ) level was detected by enzyme-linked immunosorbent assay (ELISA), myocardial infarct size ratio was detected by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining, and the change of myocardial tissue changes were detected by hematoxylin-eosin (HE) staining. Results:The survival rate of the rabbits was 93.33% (14/15) in the model group, and the success rate of MIRI modeling was 86.67% (13/15). In the model group, the ST segment (5.00±0.71) mm at I45 was higher than that before the ligation (1.20±0.27) mm, the difference was statistically significant ( P<0.01), and it was stable throughout the whole ischemia period. After ligation removal, the ST segment decreased to (3.00±0.61) mm at R15, (2.20±0.45) mm at R30, and (1.30±0.27) mm at R60. There were statistically significant differences between I45 and N, R15 and I45, and R60 and R15 (all P<0.01). The pathological Q-wave was (1.60±0.55) mm at R15, and decreased to (3.60±0.22 and 5.10±0.22) mm at R30 and R60, respectively. There were statistically significant differences between R30 and R15, R60 and R30, and R60 and R15 (all P<0.01). ST segment (6.10±0.42, 5.80±0.45, 5.60±0.22, and 5.30±0.27) mm at I45, I60, I75 and I105 respectively were higher than the ST segment (1.10±0.22) mm at N in the sustained ischemia group, and the differences were statistically significant (all P<0.01). The serum cTnⅠlevels in the model group at N, I45, R30 and R60 were (62.74±1.60, 97.60±6.36, 159.30±17.64, and 166.40±18.56) ng/L, respectively, and the difference between I45 and N was statistically significant ( P<0.05). There were statistically significant differences between R30 and I45, R60 and I45, and R30 and N (all P<0.01). The serum cTnⅠlevels in the sustained ischemia group were (69.00±4.85, 107.90±7.12, 140.60±10.96, 171.00±15.40) ng/L at N, I45, I75 and I105, respectively. There were statistically significant differences between I45 and N, I75 and I45, and I105 and I75 (all P<0.01). The infarct size ratios of the model group and the sustained ischemia group were 39.93% and (52.16±0.06) %, respectively, and the difference was statistically significant ( P<0.05). Conclusions:The method of establishing a MIRI model by ligating the left ventricular branch of the coronary artery in rabbits is simple to operate, with stable and reliable, and the success rate of modeling is high.