Abstract
It has been hypothesized that myelin acts like a mitochondrion, generating ATP across the membranes of its sheath. By calculating the proton motive force across the myelin membrane based on known values for the pH and membrane potential of the oligodendrocyte, we find that insufficient energy could be harvested from proton flow across the myelin membrane to synthesize ATP. In fact, if the respiratory chain were present in the myelin membrane, then the ATP synthase would function in reverse, hydrolyzing rather than synthesizing ATP. This calculation places the hypothesis of an energy-producing role for myelin in considerable doubt.