Measurement of mitochondrial membrane potential (MMP) in vitro

The MMP was determined using the potential-sensitive fluorescent dye, JC-1. This dual-emission probe changes color from red-orange to green as the mitochondrial membrane depolarizes. The JC-1 (5 µmol/l) was loaded onto AECs for 15 min at 37°C. The results were visualized using a confocal microscope (×650; LSM 780 NLO; Carl Zeiss, Jena, Germany). Alternatively, the fluorescence intensity was monitored using flow cytometry (BD Immunocytometry Systems, Franklin Lakes, NJ, USA) at an excitation/emission of 525/590 nm.