自发性高血压大鼠心肌壁内小动脉的重构特征观察

Remodeling features of small intramyocardial arteries in rats with idiopathic hypertension

目的观察自发性高血压大鼠(SHR)心肌壁内小动脉的重构情况及其特征。方法选取12周龄雄性SHR大鼠10只为实验组(SHR组),以周龄、性别相配的WKY大鼠为对照组(WKY组,n=10)。实验持续18周,实验开始和结束时进行血压测定。取大鼠左心室组织切片行HE染色、苦味酸-天狼猩红染色、弹力纤维和胶原纤维的双重染色(P/VB法),计算机辅助成像系统计算心肌壁内小动脉的血管壁面积(WA)、血管腔面积(LA)和血管壁面积百分比(%WA)。α-SMA免疫组化染色识别血管平滑肌细胞(VSMCs),PCNA免疫组化染色和原位末端脱氧核苷酸转移酶标记(TUNEL)分别显示心肌壁内小动脉细胞的增殖和凋亡情况,并计算增殖指数(PI)和凋亡指数(AI)。结果12周龄和30周龄SHR组收缩压(分别为172.00±9.78、200.50±14.15mmHg)明显高于WKY组(分别为123.40±5.10、116.30±9.38mmHg,P<0.01)。SHR大鼠心肌壁内直径10～69μm小动脉的WA和%WA(分别为5061±951μm2,65.0%±4.7%)明显高于WKY组(分别为3389±763μm2,44.0%±4.5%,P<0.01),而LA(2604±306μm2)显著低于WKY组(4339±971μm2,P<0.01)。SHR组心肌壁内小动脉增殖重构的部位在血管的中膜,增殖细胞表达α-SMA,提示其为VSMCs。SHR组心肌壁内小动脉中膜PI(52.79%±3.99%)明显高于WKY组(28.45%±1.87%),而AI(12.34%±2.92%)明显低于WKY组(31.69%±5.15%,P<0.01)。结论30周龄SHR大鼠心肌壁内小动脉中膜明显增厚,管腔变小,其机制可能与中层平滑肌细胞的增殖凋亡失衡有关。

Objective To investigate the features of remodeling of intramyocardial small arteries （IMSAs） in rats with idiopathic hy- pertension （SHR）. Methods 12-week-old male SHR rats （experimental group, n=10） with the age and sex matched Wlstar Kyoto rats （WKY, control group, n=10） were included in present study. Experiments were continued for 18 weeks. The blood pressure of all the animals was measured at the beginning and at the end of experiment, and ther. all the animals were sacrificed. The left ventricle tissue sections were stained with HE, Sirius-red, elasticity fibrin and collagen fibrin double staining （P/VB） for morphological evaluation of IMSAs. The wall area （WA）, luminal area （LA） and percent wall area （%WA） of IMSAs were assessed with the compute-assisted image analysis system. The vascular smooth muscle cells （VSMCs） were recognized by α-SMA immunohistochemical staining, the proliferation and apoptosis of IMSAs were demonstrated by proliferating cell nuclear antigen （PCNA） immunohistochemical staining and TdT-mediated dUTP nick-end labeling （TUNEL） technique, respectively. The apoptosis index （AI） and proliferation index （PI） were calculated respectively. Results Systolic blood pressure （SBP） in SHR group at week 12 and week 3G were significantly higher than those in WKY group （172. 00 ±9. 78mmHg vs 123.40±5. 10mmHg, 200. 50±14. 15mmHg vs 116. 30±9. 38mmHg, respectively, P〈0. 01）. The WA and %WA of IMSAs in SHR group were significantly higher than those in WKY group （50.51±951μm^2 vs 3389±763μm2 , 65.0%±4. 7% vs 44. 0%± 4. 5%, respectively, P〈0. 01）, but LA in SHR group was markedly smaller than that in WKY group （2604±306μm^2 vs 4339±971μm2, P〈0. 01）. The thickening of IMSAs was observed in media of arterioles in SHR, and immunohistochernical staining for α-SMA showed cell proliferation （PCNA-positive cells） located in the media. The PI in IMSAs media was higher than that in WKY group, while the AI was lower （52. 79%±3. 99% vs 28.45±1.87%, 12. 34%±2. 92% vs 31.69%±5. 15%, respectively, P〈0.01）. Conclusions Vessel wall thickening and decreasing luminal area were observed in IMSAs in 30-week-old SHR. Both proliferation and apoptosis of VSMCs may play an important role in the pathogenesis of IMSAs remodeling in SHR.