Overexpression of endothelin-1 induces hypertrophy of rat pulmonary arterial microvascular smooth muscle cells via Akt/mTOR pathway]

To investigate the effects of endothelin-1 (ET-1) overexpression on hypertrophy of the rat pulmonary arterial microvascular smooth muscle cells (RPMCs) in vitro.Lung tissue perfusion method was used to obtain the primary RPMCs, and then the cells were transiently transfected with ET-1 plasmids or empty vectors via Lipofectamine. Flow cytometry was used to determine the distributions of the cell cycle and cell size of RPMCs. Immunofluorescence staining and Western blotting were used to determine the level of alpha-smooth muscle actin. The ratio of the protein/DNA of the transfected RPMCs was also calculated. Western blotting was used to examine the levels of phosphorylations of protein kinase B/Akt, mTOR, and ERK1/2.Primary RPMCs were isolated successfully. Overexpression of ET-1 resulted in a significant increase in total protein synthesis, expression of alpha-SMA, as well as increased cell size. Western blotting results showed that overexpression of ET-1 resulted in increased phosphorylation of Akt, mTOR and a decreased phosphorylation of ERK1/2 in RPMC.ET-1 overexpression induces RPMC hypertrophy and activation of Akt/PKB-mTOR pathway may be involved in the mechanism, with important implications for the pathogenesis of vascular remodeling in pulmonary arterial hypertension.