The expression of Rho kinase of pulmonary arterial smooth muscle cells exposed to hypoxia

Objective:To explore the effects of hypoxia on expression of Rho kinase and proliferation of rat pulmonary arterial smooth muscle cells(PASMC).Methods: Cultured PASMC were exposed to normoxia and hypoxia for 12、24 and 48 h.Viability of PASMC was examined by MTT assay.The cell cycle was analyzed by flow cytometry.Western blot was used to assess the levels of Rho kinase after primarily cultured rat PASMC were exposed to hypoxia for 12、24 and 48 h. Results: The result of MTT was increased in PASMC to hypoxia for 12 h compared with PASMC in normoxia.After exposure of PASMC to hypoxia for 24 h,the result of MTT peaked,then declined in 48 h,but still higher than that of PASMC when exposed to normoxia.Analysis of cell cycle indicated that the ability of cell proliferation increased significantly in PASMC exposed to hypoxia compared with normoxia.Rho kinase level was higher in PASMC exposed to hypoxia compared with normoxia.Conclusion: Hypoxia stimulates proliferation of PASMC and promotes PASMC into the phase of mitosis.Expression of Rho-kinase is increased in proliferated PASMC induced by hypoxia and the increased expression of Rho-kinase maybe one of important pathogenesis in hypoxia-induced proliferation of PASMC.