Abstract: AIM: To observe the effect of levcromakalim (Lev) on endthelin-1(ET-1) induced proliferation and the expression of protein kinase C (PKC) in cultured rat vascular smooth muscle cells (VSMCs).Methods: VSMCs were isolated from rat aorta and were cultured with different concentrations of Lev in vitro after stimulated to proliferation by ET-1(10^-8mol·L^-1). Vitality of VSMCs was detected by MTT;DNA replication was evaluated by 3H-TdR method.Flow cytometry was used to analyze cell cycle and apoptosis.The expression of PKCαprotein and mRNA were determined by Western blot and reverse transcription-polymerase chain reaction (RT-PCR).Results: Vitality of VSMCs and 3H-TdR intermingle rate were decreased (P<0.05) in a dose dependent manner which indicated Lev inhibited VSMCs proliferation by inducing ET-1.Levcromakalin increased the ratio of VSMCs apoptosis (P<0.01).The cell cycle was blocked at G0 G1 phase by Lev in a dose dependent manner (P<0.05).Levcromakalim decreased the expression of PKCαprotein and mRNA in VSMCs (P<0.05).Conclusion: Levcromakalim inhibits VSMCs proliferation by inducing ET-1 through reducing the expression PKCα.

Key words: levcromakalim, vascular smooth muscle cells, proliferation, protein kinase C