Analysis using cationic lipophilic dyes such as JC-1, TMRE (tetramethyl rhodamine ethyl ester), DiOC6 (3), DiIC1 (5), CMXRos (MitoTracker Red), LDS-751, and rhodamine 123, which localize themselves across the inner mitochondrial membrane. Loss of the membrane potential is detected as a decrease in membrane staining or the fluorescence intensity, as the transmembrane potential decreases.