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

摘要： 目的　建立7日龄大鼠心肌梗死模型的制备方法。方法　将34只出生7日龄(P7)SD大鼠随机分为假手术 组(Sham组,n=17)和急性心肌梗死组(AMI组,n=17)。AMI组大鼠行冠状动脉左前降支(LAD)结扎手术以建立 心肌梗死模型;Sham组仅开胸,不结扎LAD。术后1 d,通过TTC染色明确LAD结扎效果;术后21 d,通过HE染色 评估心脏组织损伤程度,通过天狼猩红染色评估心肌组织纤维化程度,通过心脏/体质量比和心脏超声评估心脏结 构和功能变化。结果　成功制备P7新生大鼠心肌梗死模型,术后1 d TTC染色证实LAD结扎成功。术后21 d,HE 染色显示,与Sham组相比,AMI组心脏组织损伤明显。天狼猩红染色显示,AMI组心肌纤维化面积为(6.44± 2.06)%,显著高于Sham组的(1.53±0.09)%,差异有统计学意义(P<0.001)。心脏超声显示,AMI组大鼠的射血 分数(EF)为(75.57±3.86)%,显著低于Sham组的(85.61±3.15)%;短轴缩短率(FS)为(44.53±3.82)%,显著低 于Sham组的(55.34±3.86)%(均P<0.01)。心脏/体质量比亦显著下降(均P<0.05)。结论　本研究成功建立并 验证了P7大鼠心肌梗死模型,该模型在术后21 d可呈现典型的心肌重塑特征,包括广泛的心肌纤维化、室壁变薄 及心室扩张,并伴有心脏收缩功能下降。本模型制备方法稳定、评价体系完整,可为后续心肌再生与修复研究提供 可靠的实验基础。

关键词: 心肌梗死, 新生大鼠, 心肌再生, 动物模型