Supplementary Material for: Smooth Muscle Cell Relaxation Worsens Aortic Dilatation and Clinical Presentation in a BAPN/Angiotensin II-Induced Aortic Dissection Model in Rats

Introduction: Beta-aminopropionitrile (BAPN) administration is a chemically induced model for preclinical aortic pathologies research. Angiotensin II (AngII) has been widely used to promotes aortic dissections in mice. Here, we provide insight on a modified aortic dissection model in rats. The effect of smooth muscle cell (SMC) relaxation with vasodilators is studied in this model. Methods: Forty Sprague-Dawley rats were divided in 4 groups: control, isosorbide dinitrate (ISDN, 30 mg/kg/day) in the drinking water, BAPN (0.02%) in the food, BAPN + ISDN (same doses). Thoracic and abdominal aortic diameters were evaluated through transthoracic ultrasound echography. After 6 weeks, all rats were infused with AngII (1 mg/kg/day) subcutaneously. Survival and type of aortic events were numbered. Histological and histochemical analyses of aorta were performed. Results: Initial telesystolic ascending aorta diameters were equal in all groups and became significantly larger in the BAPN + ISDN group compared to the BAPN group (control: 3.37 ± 0.17 mm, ISDN: 3.49 ± 0.16 mm, BAPN: 3.53 ± 0.13 mm, BAPN + ISDN: 3.61 ± 0.16 mm, analysis of variance p p = 0.029) and produced a large panel of aortic events. Association of ISDN and BAPN significantly reduces survival (p = 0.001) and provides more aortic events compared to BAPN alone (p = 0.031). In both BAPN-treated groups, orcein staining revealed split and dissected elastic fibers in the media, alcian blue staining showed mucoid degeneration of the aortic wall, and Perls-diaminobenzidine staining revealed an accumulation of Fe2+. Conclusion: SMC relaxation with ISDN increases aortic dilatation, worsens aortic prognosis, and reproduces human histological findings in a low-dose BAPN/AngII-induced aortic dissection model in rats.

引言：β-氨基丙腈（Beta-aminopropionitrile, BAPN）给药是用于临床前主动脉病变研究的化学诱导模型。血管紧张素II（Angiotensin II, AngII）已被广泛用于构建小鼠主动脉夹层模型。本研究针对改良的大鼠主动脉夹层模型展开探究，旨在评估血管舒张剂对平滑肌细胞（smooth muscle cell, SMC）舒张的影响。方法：将40只斯普拉格-道利大鼠随机分为4组：对照组、饮用水给予硝酸异山梨酯（isosorbide dinitrate, ISDN, 30 mg/kg/天）组、饲料添加0.02% β-氨基丙腈（BAPN）组、BAPN联合ISDN组（两组药物剂量保持一致）。通过经胸超声心动图评估胸主动脉与腹主动脉直径。造模6周后，对所有大鼠皮下输注血管紧张素II（AngII, 1 mg/kg/天），记录大鼠生存情况及主动脉事件类型，并开展主动脉组织学与组织化学分析。结果：各组大鼠初始收缩末期升主动脉直径无显著差异；BAPN联合ISDN组的升主动脉直径显著大于单纯BAPN组[对照组：3.37±0.17 mm，ISDN组：3.49±0.16 mm，BAPN组：3.53±0.13 mm，BAPN+ISDN组：3.61±0.16 mm，方差分析p=0.029]，且可诱发多种主动脉事件。与单纯BAPN组相比，ISDN联合BAPN可显著降低大鼠生存率（p=0.001），并增加主动脉事件发生频次（p=0.031）。在两个BAPN处理组中，地衣红染色（orcein staining）可见主动脉中膜弹性纤维断裂、解离；阿尔辛蓝染色（alcian blue staining）显示主动脉壁出现黏液样变性；珀尔斯-二氨基联苯胺染色（Perls-diaminobenzidine staining）可见Fe²+沉积。结论：在大鼠低剂量BAPN/AngII诱导的主动脉夹层模型中，通过ISDN实现平滑肌细胞舒张，可加重主动脉扩张、恶化主动脉预后，并复现人类主动脉病变的组织学特征。