[Effect of Rho kinase on hypoxia stimulated proliferation of pulmonary arterial smooth muscle cells].

OBJECTIVE: To study whether Rho kinase is involved in the proliferation of pulmonary arterial smooth muscle cells (PASMCs) induced by hypoxia. METHODS: Rat's PASMCs were isolated and cultured. Methyl thiazolyl tetrazolium (MTT) was used to determine the growth of cells. The cell cycle was analyzed by flow cytometry. Western blot was used to assess the expression of Rho kinase. RESULTS: The results of MTT showed that the number of PASMCs was increased after exposure to low oxygen tension for 12 hours compared with PASMCs in normoxia. After exposure of PASMCs to hypoxia for 24 hours,the cellular proliferation peaked,and was higher than that of PASMCs exposed to normal oxygen tension, hypoxia and Y27632 (Rho kinase inhibitor) groups,then it declined when exposed for 48 hours. Analysis of cell cycle indicated that the ability of cell proliferation increased significantly in PASMCs exposed to hypoxia compared with normoxia. Rho kinase level was higher in PASMCs exposed to hypoxia compared with normoxia. CONCLUSION: Hypoxia stimulates proliferation of PASMCs and promotes PASMCs into the phase of mitosis. The expression of Rho kinase is increased in PASMCs that are exposed to hypoxia, and it shows that Rho kinase is activated by hypoxia in PASMCs. Rho kinase maybe involve in the proliferation of PASMCs induced by hypoxia.