慢性栓塞性肺动脉高压大鼠肺动脉重塑与尾加压素Ⅱ及其受体的表达

目的 研究尾加压素Ⅱ(U Ⅱ)蛋白和mRNA及U Ⅱ受体(UT)mRNA在慢性栓塞性肺动脉高压大鼠肺动脉的表达,探讨其在病程中的作用.方法 雄性Wistar大鼠,麻醉后经颈静脉注入体外制备的血栓栓子,2周后同法进行2次栓塞,造模成功大鼠分为2周组、4周组、8周组、12周组,全程腹腔注射抗纤维溶解剂氨甲环酸,达到目标日期后行以下检查:(1)测量平均肺动脉压(mPAP);(2)用免疫学检验和原位杂交的方法检测不同节段肺动脉U Ⅱ蛋白和mRNA表达及UT mRNA表达;(3)在光镜下观察肺动脉显微结构的变化,测定肺动脉相对中膜厚度(PAMT)和管壁面积/管总面积(WA/TA).采用SPSS 13.0软件,所有数据以-x±s表示,组间比较采用单因素方差分析,组间差异采用LSD方差分析.结果 (1)栓塞后4、8及12周组的大鼠mPAP值分别为(19.9±6.2)mm Hg(1 mm Hg=0.133 kPa)、(23.8±4.1)mm Hg、(27.4±5.4)mm Hg,较对照组明显升高(F值为13.75,P＜0.01),PAMT百分比分别为42.6±11.16、47.82±10.02、53.79±10.41,WA/TA百分比分别为22.75±6.79、25.32±4.90、27.05±7.71,较对照组均明显增大(F值分别为5.52和6.61,P均＜0.01);(2)栓塞后肺动脉U Ⅱ蛋白和U Ⅱ mRNA以及UT mRNA表达上调,细小动脉较中型动脉变化更为明显,4、8及12周组肺细小动脉U Ⅱ mRNA和UT mRNA及U Ⅱ蛋白平均吸光度值分别为0.138±0.019、0.144±0.022、0.173±0.021和0.126±0.028、0.146±0.029、0.157±0.025,与对照组相比明显升高(F值分别为30.39、30.78和14.49,P均＜0.01),随着栓塞时间的延长,表达呈明显增加的趋势;(3)肺细小动脉U Ⅱ蛋白和mRNA及UT mRNA的平均吸光度值均与mPAP、PAMT呈正相关关系(r值分别为0.822、0.866、0.846;0.675、0.712、0.756,P均＜0.01).结论 慢性栓塞性肺动脉高压大鼠出现明显肺动脉重构,尾加压素Ⅱ蛋白和mRNA及其UT mRNA在肺动脉表达明显上调,其动态变化与肺动脉高压、肺血管重构的病理过程明显相关.

Expressions of urotensin Ⅱ and its receptor in pulmonary arteries in rats with chronic thromboembolic pulmonary hypertension

OBJECTIVE: To investigate the expressions of Urotensin II (UII) protein and mRNA and its receptor (UT) mRNA of medium and small pulmonary arteries of rats with chronic thromboembolic pulmonary hypertension. METHODS: The Wistar rats were injected thrombi through the jugular vein 2 times in 2 weeks and tranexamic acid was injected peritoneally once daily during the experiment to prevent thrombolysis. The mean pulmonary artery pressure (mPAP) was measured using right cardiac atheterzation. The expressions of UII protein in pulmonary arteries were studied by immunohischemistry with a polycolonal antibody. The expressions of UII mRNA and UT mRNA were detected by in situ hybridization using UII and UT oligonuclear probes. The changes of structures in pulmonary vessle were observed, including relative medial thickness of pulmonary artery (PAMT) and vessle wall area/total vessle area (WA/TA). RESULTS: The mPAP of the 4 weeks to the 12 weeks groups were (19.9 +/- 6.2) mm Hg (1 mm Hg = 0.133 kPa), (23.8 +/- 4.1) mm Hg and (27.4 +/- 5.4) mm Hg, higher than that of the control group (F = 13.75, P < 0.01, respectively). The PAMT of the 4 weeks to the 12 weeks groups were (42.6 +/- 11.16)%, (47.82 +/- 10.02)% and (53.79 +/- 10.41)%, and WA/TA of the 4 weeks to the 12 weeks groups were (22.75 +/- 6.79)%, (25.32 +/- 4.90)% and (27.05 +/- 7.71)%, both changed significantly as compared to the control group (F = 5.52 and 6.61, P < 0.01, respectively; P < 0.05 in 4 weeks group; P < 0.01 in 8 weeks and 12 weeks groups, respectively). The expressions of UIIprotein, UII mRNA and UT mRNA in the 4 weeks to the 12 weeks groups were obviously higher than the control group (F = 30.39, 30.78 and 14.49, P < 0.01, respectively), and their expressions were more marked in the small pulmonary arteries than in medium pulmonary arteries. The expressions of UIIprotein, UII mRNA and UT mRNA were positively correlated with mPAP and PAMT. The pulmonary vascular remodeling was time-dependently aggravated after embolism (r: 0.822, 0.866 and 0.846; 0.675, 0.712 and 0.756, P < 0.01, respectively). CONCLUSIONS: The expressions of UII protein, UII mRNA and UT mRNA of pulmonary arteries in the animal models were higher than those in the control group. These dynamic changes of UII mRNA, UIIprotein and UT mRNA may contribute to the development of pulmonary hypertension and vascular remodeling after pulmonary thromboembolism.