Our previous studies found that mitochondrial uncouplers CCCP and niclosamide inhibited artery constriction and the mechanism involved AMPK activation in vascular smooth muscle cells.BAM15 is a novel type of mitochondrial uncoupler.The aim of the present study is to identify the vasoactivity of BAM15 and characterize the BAM15-induced AMPK activation in vascular smooth muscle cells (A10 cells).BAM 15 relaxed phenylephrine (PE)-induced constricted rat mesenteric arteries with intact and denuded endothelium.Pretreatment with BAM15 inhibited PE-induced constriction of rat mesenteric arteries with intact and denuded endothelium.BAM 15,CCCP,and niclosamide had the comparable IC50 value of vasorelaxation in PE-induced constriction of rat mesenteric arteries.BAM15 was less cytotoxic in A10 cells compared with CCCP and niclosamide.BAM15 depolarized mitochondrial membrane potential,induced mitochondrial fission,increased mitochondrial ROS production,and increased mitochondrial oxygen consumption rate in A10 cells.BAM15 potently activated AMPK in A10 cells and the efficacy of BAM15 was stronger than that of CCCP,niclosamide,and AMPK positive activators metformin and AICAR.In conclusion,BAM15 activates AMPK in vascular smooth muscle cells with higher potency than that of CCCP,niclosamide and the known AMPK activators metformin and AICAR.The present work indicates that BAM15 is a potent AMPK activator.