[Endothelin-1 overexpression inhibits rat pulmonary arterial microvascular smooth muscle cell apoptosis via Akt/PKB pathway].

OBJECTIVE: To investigate the effects of endothelin-1 (ET-1) overexpression on apoptosis of the rat pulmonary arterial microvascular smooth muscle cells (RPMC) in vitro. METHODS: Primary RPMC obtained from the pulmonary artery and lung microvasculature were identified by immunofluorescence staining and electron microscope technique. The RPMC was transient transfected with the pMEXneo-ET1 and pCDNA5-FRT-TO-ET1-3'UTR plasmids as well as the empty vector respectively via lipofectamine. Flow cytometry was used to assess the cell cycle and apoptosis of RPMC. Akt and Caspase-3 expressions were detected by Western blot and real time RT-PCR. RESULTS: The mRNA of ET(A) expression was significantly higher than that of ET(B) receptor in primary RPMC. Flow cytometry analysis revealed significantly reduced apoptosis in ET-1 transfected RPMC compared to that in vehicle transfected RPMC. Overexpression of ET-1 in RPMC also significantly increased the phosphorylation of Akt and reduced the cleaved Caspase-3 expression. CONCLUSIONS: Overexpression of the ET-1 inhibited RPMC apoptosis and activated Akt/PKB-Caspase-3 signaling pathway, which might be responsible for ET-1 induced the pulmonary microvascular arteries remodeling.