what happens to mitochondrial respiration when there is an increase in permeability of the inner mitochondrial membrane to protons

Question

What would happen to the mitochondrial proton gradient, mitochondrial respiration (mitochondrial oxygen consumption), and the NADH oxidation rate in cells treated with carbonyl cyanide-4-trifluoromethoxyphenylhydrazone (FCCP), a molecule that increases the permeability of the inner mitochondrial membrane to protons?

Answer 1

Maintaining the proton gradient is important for establishing the electron motive force that ultimately drives ATP production via ATP synthase. If you disrupt the proton gradient, in this case y adding FFCP, then you decrease the number of ATP produced by ATP synthase. Additionally, it's important to remember that oxygen is the final electron acceptor and will form water. It's the movement of electrons through the complexes that results in net movement of protons into the inter membrane space. So, putting it all together, if you have a mitochondrial membrane with increased permeability, you decrease the ability to pump hydrogens into the inter membrane space and you get a build up of oxygen inside the mitochondrial matrix and a reduction of NADH oxidation as well ( this will stay in its reduced form). Hope this helps :)