On measurement of mitochondrial transmembrane potential with fluorescent probes

It is commonly thought that rhodamine, cyanine, and some other fluorescent dyes are specific potential-dependent ones and that they allow quantitatively measuring the transmembrane potential in mitochondria and cells. However, a critical analysis of the experimental data shows that this statement is only a supposition. In reality, widely used fluorescent probes, such as merocyanine 540, Dis-C3-(5), safranin O, or 8-anilino-1-naphthalene sulfonate, poorly bind to the native mitochondria and weakly react to their energization or uncoupling. It can be concluded that calculations of the magnitude of the transmembrane potential of the inner mitochondrial membrane in response to addition of succinate, ATP, or dinitrophenol from the change in fluorescence of these probes are incorrect.