The straight forward way to see membrane potential is as the spark plug of metabolism. The inner membrane of mitochondria is where food, oxygen, and water get switched to vigor and where aerobic metabolism comes to pass.
Positioned right up along side the inner membrane is the mitochondrial DNA and so it is significantly susceptible to boosts in endogenous free radicals (termed reactive oxidative species, ROS, or reactive oxygen metabolites, ROM). Harm to mitoDNA is implicated in all chronic disease. This happens because the membrane becomes like swiss cheese. Unrestored oxidation leaves holes in the membrane where free radicals steal away rather than be sated by enzymes like glutathione, SOD, catalyses, etc.