Effects of inhibiting myosin light chain kinase on endothelin-1 induced proliferation and apoptosis of pulmonary arterial smooth muscle cells in rats

AIM: To investigate the effect of inhibiting myosin light chain kinase(MLCK) on endothelin-1(ET-1) induced proliferation and apoptosis of rat pulmonary artery smooth muscle cells(PASMCs). METHODS: Rat PASMCs were cultured and stimulated with ET-1. The cells were randomly divided into control group, ET-1 group and ET-1+MLCK inhibitor group(ET-1+M). Western blotting, MTT assay, ³H]-TdR incorporation and flow cytometry were employed to test the expression of myosin light chain(MLC) and MLCK, cell proliferation, cell cycle and apoptotic rate of PASMCs,respectively. The phosphorylation of MLC was determined by glycerol-PAGE coupled with Western blotting. RESULTS: Compared with control group, the protein expression of MLCK and MLC phosphorylation significantly enhanced after ET-1 stimulation. ET-1 markedly induced the proliferation and decreased the percentage of apoptotic rate in the PASMCs. However, pretreatment with ML-7, a MLCK inhibitor, significantly reversed the above effects induced by ET-1. CONCLUSION: MLCK inhibitor effectively inhibits the ET-1-induced proliferation and the cell cycle progression.