Methods to Measure Membrane Potential and Permeability Transition in the Mitochondria During Apoptosis

Mitochondrial membrane permeabilization (MMP) constitutes an early event of the apoptotic process. MMP affects both mitochondrial membranes. Inner MMP leads to the dissipation of the inner transmembrane potential and outer MMP culminates in the efflux of apoptogenic factors. The exact molecular mechanisms of MMP are still controversial. A growing body of data suggests that the cell death regulatory activity of Bcl-2 family members depends, at least in some instances, on their ability to modulate the opening of the mitochondrial permeability transition pore complex. Here, we will detail some experimental protocols designed to measure mitochondrial membrane potential and permeability transition, either in intact cells or in isolated mitochondria.