Effects of PIO on mitochondrial membrane potential and AMP/ATP ratio in VSMCs. Serum-deprived VSMCs were treated with: (A) PIO (30 μM, 1 or 3 hr), CCCP (50 μM, 1 hr), or vehicle control followed by fluorescence microscopy analysis of mitochondrial membrane potential; or (B) PIO (30 μM, 3 hr) or vehicle control followed by LC-MS/MS MRM analysis of AMP/ATP ratio. n.s. not significant compared with vehicle control; n = 4.