关键词: 心肌梗死, 新生大鼠, 心肌再生, 动物模型

Abstract: Objective　To establish myocardial infarction model of postnatal 7 d rat.Methods　Thirty four postnatal day 7 (P7) Sprague-Dawley rats were randomly assigned to a sham-operated group (Sham group, n=17) and an acute myocardial infarction group (AMI group, n=17). Myocardial infarction was induced in the AMI group by ligating the left anterior descending (LAD) coronary artery, while the Sham group underwent thoracotomy without LAD ligation. On postoperative day 1, TTC staining was performed to confirm the LAD ligation efficacy. On postoperative day 21, the extent of cardiac tissue damage was assessed by hematoxylin and eosin (HE) staining, myocardial fibrosis was evaluated by picrosirius red staining, and changes in cardiac structure and function were examined via heart/body weight ratio and echocardiography.Results　The myocardial infarction model in P7 neonatal rats was successfully established, with TTC staining confirming effective LAD ligation on day 1 post-surgery. On day 21 post surgery, compared with Sham group, HE staining revealed significant cardiac damage in AMI group. Picrosirius red staining indicated that the myocardial fibrosis area was (6.44±2.06)% in the AMI group, which was significantly higher than (1.53±0.09)% in the Sham group (P<0.001). Echocardiography showed that the ejection fraction (EF) and fractional shortening (FS) were(75.57± 3.86)% and(44.53±3.82)% in the AMI group, significantly lower than (85.61±3.15)% and (55.34±3.86)% in the Sham group, respectively (all P<0.01). The heart/body weight ratio was also significantly decreased in the AMI group (P<0.05). Conclusion　This study successfully established and validated a P7 rat myocardial infarction model. This model exhibits typical characteristics of cardiac remodeling at 21 days post-infarction, including extensive myocardial fibrosis, ventricular wall thinning, chamber dilation, and impaired systolic function. The established protocol is reliable, and the comprehensive evaluation system provides a solid experimental foundation for future research on mammalian myocardial regeneration and repair.

Key words: myocardial infarction, neonatal rat, heart regeneration, animal model