[Expression and activity of RhoA/Rho kinase in remodeling of high blood flow pulmonary vessels.].
摘要
OBJECTIVE: High pulmonary blood flow induced pulmonary hypertension (PH) is often associated with increased vasoconstriction and deteriorating pulmonary artery remodeling, of which the exact mechanism has not been completely elucidated. The involvement of RhoA/Rho-kinase pathway has been demonstrated in the pathogenesis of hypoxia and monocrotaline induced PH. Thus the purpose of this study was to test whether RhoA/Rho-kinase pathway is involved in the process of high pulmonary flow induced pulmonary artery remodeling in rats. METHODS: Wistar rats aged 4 weeks in the shunt group underwent left common carotid artery-external jugular vein shunt operation, those in control group received sham-operation. At weeks 1, 2, 4 and 8 of the study, rats underwent right ventricular systolic pressure (RVSP) measurement; blood gases were analyzed to calculate Qp/Qs. The morphologic alterations of the pulmonary arteries were observed under optical microscope. The mean percentage of media wall thickness (%MT) was also measured to assess the extent of medial wall thickness of moderate size pulmonary arteries. Proliferating smooth muscle cells (SMCs) were evaluated by proliferating cell nuclear antigen (PCNA) immunohistochemical staining. Apoptotic SMCs were detected by TUNEL method. RhoA activity in pulmonary arteries was detected using pull down assay. Rho kinase activity was quantified by the extent of MYPT1 phosphorylation with Western blotting. The expression of RhoA and Rho kinase (ROCK2) was also detected with Western blotting. RESULTS: Carotid artery-jugular vein shunt resulted in high pulmonary blood flow, of all rats in shunted groups, the mean Qp/Qs was 2.26 +/- 0.35, which were all considered large shunts. Compared with the control group, RVSP in shunt group increased significantly at both week 1 and week 8 (t = 8.799, t = 5.332, respectively, P < 0.01). Compared with the control group, moderate pulmonary artery medial wall thickening characterized by SMCs hyper-proliferat