Long-term inhibition of Rho kinase with fasudil attenuates high flow induced pulmonary artery remodeling in rats.

Accumulating evidences have demonstrated that RhoA/Rho-kinase pathway plays a pivotal role in various cellular functions. The aim of this study was to explore whether RhoA/Rho-kinase pathway is involved in the pathogenesis of high flow induced pulmonary hypertension and whether long-term inhibition of RhoA/Rho-kinase pathway with fasudil could attenuate high flow induced pulmonary artery remodeling in rats. Wistar rats in the shunt groups and treated groups were underwent left common carotid artery-external jugular vein shunt operation, rats in control groups were sham-operated animals. Rats in treated groups received fasudil treatment, the others received same dose of saline. At week 4, 8 of the study, rats were underwent haemodynamics measurements, pulmonary artery morphologic assessments, detection of pulmonary artery smooth muscle cells (SMCs) proliferation and apoptosis. RhoA and Rho-kinase activity in pulmonary arteries were also analyzed. Compared with the control groups, exposure to high blood flow induced a significant elevation of right ventricle systolic pressure at week 8, significant increase of the mean percentage of media wall thickness (%MT) in moderate size pulmonary arteries both at weeks 4 and 8, marked elevation of right ventricle (RV) to left ventricle plus septum (LV+SP) weight ratio at week 8, significant increase of PCNA-positive SMCs percentage at week 4 and significant decrease of TUNEL-positive SMCs percentage both at weeks 4 and 8. High pulmonary blood flow also induced 3.19+/-0.28-fold increase of RhoA and 3.63+/-0.52-fold increase of Rho-kinase over the control group at week 4, 1.57+/-0.35-fold increase of RhoA and 2.36+/-0.39-fold increase of Rho-kinase over the control group at week 8. Compared with the shunt groups, fasudil treatment significantly suppressed Rho-kinase activity at both weeks 4 and 8, improved pulmonary hypertension at week 8, attenuated right ventricular hypertrophy at week 8, and enhanced pulmonary vascular remodeling both at weeks 4 and 8, which were associated with suppressed pulmonary artery smooth muscle cells proliferation at week 4 and apoptosis both at weeks 4 and 8. These results indicated that RhoA/Rho-kinase mediated pathway participated in the process of high flow induced pulmonary artery remodeling; inhibition of Rho kinase with fasudil could attenuate pulmonary artery remodeling.