缺氧性肺动脉高压新生大鼠肺血管重塑与肺血管HIF-1α、ET-1、iNOS表达的相关性研究

Association between pulmonary vascular remodeling and expression of hypoxia-inducible factor-1α, endothelin-1 and inducible nitric oxide synthase in pulmonary vessels in neonatal rats with hypoxic pulmonary hypertension

摘要:

目的：了解缺氧性肺动脉高压（HPH）新生大鼠肺血管重塑与肺血管HIF-1α、ET-1、iNOS表达的相关性。方法：建立HPH新生大鼠模型，检测平均肺动脉压力（mPAP）；并计算肺小动脉中层壁厚占肺小动脉的外径百分比（MT%）、肺小动脉管壁中层横截面积占肺小动脉总横截面积的百分比（MA%）作为肺血管重塑指标；免疫组化法检测新生大鼠肺组织中HIF-1α、ET-1、iNOS反应强度及mRNA表达；进行肺血管重塑与HIF-1α、ET-1、iNOS mRNA相关性分析。结果：缺氧3、5、7、10、14、21 d，新生大鼠mPAP持续增高，与对照组相比差异有统计学意义（P＜0.05）。缺氧7 d后MT%、MA%明显高于对照组（P<0.05）。肺组织中HIF-1α表达在缺氧3、5、7、10 d时显著高于对照组（P＜0.05）,其mRNA表达在3、5、7 d高于对照组（P＜0.05）；ET-1表达在缺氧3、5、7 d时显著高于对照组（P＜0.05），其mRNA表达在缺氧3 d时高于对照组（P＜0.05）；iNOS蛋白及mRNA表达在缺氧3、5、7 d 时均显著高于对照组（P＜0.05）。MT%和MA%与HIF-1α mRNA呈正相关（r分别为 0.835、0.850，P<0.05）。结论：新生大鼠缺氧7 d后肺血管出现重塑；HIF-1α、ET-1及iNOS共同参与了新生大鼠HPH的发生及发展。

Abstract:

OBJECTIVE: To investigate the association between pulmonary vascular remodeling and expression of hypoxia-inducible factor-1α (HIF-1α), endothelin-1 (ET-1) and inducible nitric oxide synthase (iNOS) in pulmonary vessels in neonatal rats with hypoxic pulmonary hypertension (HPH). METHODS: A neonatal rat model of HPH was established as an HPH group, and normal neonatal rats were enrolled as a control group. The mean pulmonary arterial pressure (mPAP) was measured. The percentage of medial thickness to outer diameter of the small pulmonary arteries (MT%) and the percentage of medial cross-section area to total cross-section area of the pulmonary small arteries (MA%) were measured as the indicators for pulmonary vascular remodeling. The immunohistochemical reaction intensities for HIF-1α, ET-1 and iNOS and their mRNA expression in lung tissues of neonatal rats were measured. Correlation analysis was performed to determine the relationship between pulmonary vascular remodeling and mRNA expression of HIF-1α, ET-1 and iNOS. RESULTS: The mPAP of the HPH group kept increasing on days 3, 5, 7, 10, 14, and 21 of hypoxia, with a significant difference compared with the control group (P<0.05). The HPH group had significantly higher MT% and MA% than the control group from day 7 of hypoxia (P<0.05). HIF-1α protein expression increased significantly on days 3, 5, 7 and 10 days of hypoxia, and HIF-1α mRNA expression increased significantly on days 3, 5 and 7 days of hypoxia in the HPH group compared with the control group (P<0.05). ET-1 protein expression increased significantly on days 3, 5 and 7 days of hypoxia and ET-1 mRNA expression increased significantly on day 3 of hypoxia in the HPH group compared with the control group (P<0.05). Both iNOS protein and mRNA expression were significantly higher on days 3, 5 and 7 days of hypoxia than the control group (P<0.05). Both MT% and MA% were positively correlated with HIF-1α mRNA expression (r=0.835 and 0.850 repectively; P<0.05). CONCLUSIONS: Pulmonary vascular remodeling is developed on day 7 of hypoxia in neonatal rats. HIF-1α, ET-1 and iNOS are all involved in the occurrence and development of HPH in neonatal rats.