Rho激酶在低氧大鼠肺小动脉表达的研究

目的探讨Rho激酶（ROCKⅠ和ROCKⅡ）在慢性低氧大鼠肺小动脉产生和表达的变化及其在低氧性肺动脉高压形成过程中的作用。方法将36只健康雄性SD大鼠随机分为正常组、低氧1d、3d、1周、2周和3周组，每组6只。低氧处理为常压间断低氧，每天8h，各低氧组分别低氧1d、3d、1周、2周和3周。采用微导管法测定大鼠平均肺动脉压（mPAP）。分离和称量大鼠右心室（RV）及左心室加室间隔（LV＋S）重量，计算出RV／（LV＋S）。应用免疫组化法测定大鼠肺组织Rho激酶蛋白的表达，原位杂交法测定Rho激酶mRNA的表达。结果大鼠mPAP、RV／（LV＋S）随低氧时间延长出现升高趋势（P〈0．05）。正常组与各低氧组的肺小动脉壁的管壁厚度占外径的百分比（WT％）和管壁面积占血管总面积的百分比（WA％）均随低氧时间的延长出现升高趋势，低氧3周组大鼠的WT％和WA％均高于正常组（P〈0．05）。ROCKⅠ、ROCKⅡ免疫组化阳性染色强度和ROCKⅠ mRNA、ROCKⅡmRNA原位杂交阳性染色强度随着低氧时间的延长均出现升高趋势，低氧3周组ROCKⅠ、ROCKⅡ免疫组化阳性染色和ROCKⅠmRNA、ROCKⅡmRNA原位杂交阳性染色均显著高于正常组（P〈0．05）。ROCKI免疫组化、ROCKⅠmRNA原位杂交、ROCKⅡ免疫组化及ROCKⅠmRNA原位杂交阳性染色强度均与mPAP、wA％和wT％呈正相关（r分别为0．404、0．267和0．263；0．500、0．263和0．260；0．490、0．295和0．286；0．579、0．251和0．254，P均〈0．05）。结论低氧可导致Rho激酶产生和表达增加。Rho激酶可能通过促进肺小动脉收缩和肺小动脉重构参与低氧性肺动脉高压的发生。

Research on Rho-kinase Expression in Pulmonary Arterioles of Rat Exposed to Hypoxia

OBJECTIVE: To evaluate the expression and the role of Rho-kinase (ROCK I and ROCK II )in the development of hypoxic pulmonary hypertension of rat. METHODS: Thirty six of adult male SD rats were randomly divided into six groups; one group was exposed to air as normal control, the other five groups were exposed to isobaric hypoxia for 1 day, 3 days, 1 week, 2 weeks and 3 weeks respectively. Microtube method was used to measure the mean pulmonary arterial pressure (mPAP). The right ventricle (RV) and left ventricle plus atrial ventricular septum (LV+S) were isolated and weighed to calculate the value of RV/(LV+S). The amounts of Rho-kinase and Rho-kinase mRNA in rat pulmonary artery were determined by immunohistochemistry, in situ hybridization and image analysis. RESULTS: The mPAP and RV/(LV+S) values increased with time prolongation of rats exposed to hypoxia (P<0.05). The ratio of arteriole wall thickness/vascular external diameter(WT%) and vascular area/total vascular area(WA%) went forward to a height with exposing rats to hypoxia for a long time; WT% and WA% of hypoxia group rats exposed for 3 weeks were significantly higher than that of control group (P<0.05). All of ROCK I , ROCK II, ROCK I mRNA and ROCK II mRNA in pulmonary arterioles got the enhanced positive signals of immunohistochemistry staining or in situ hybridization with prolonging the time of rats exposed to hypoxia. The hypoxia group for 3 weeks got significantly stronger staining signals of Rho-kinase and Rho-kinase mRNA in pulmonary arterioles than that of control group (P<0.05). The positive staining of ROCK I , ROCK I mRNA, ROCK II or ROCK II mRNA in pulmonary arterioles all positively related with mPAP, WA% and WT% (r=0.404, 0.267 and 0.263; 0.500, 0.263 and 0.260; 0.490, 0.295 and 0.286; 0.579, 0.251 and 0.254) (P<0.05). CONCLUSIONS: Hypoxia led Rho-kinase and Rho-kinase mRNA to have an increased expression. Rho-kinase may play a role in the development of hypoxic pulmonary hypertension by contracting and remodeling pulmonary arterioles.