Fig. 4.

Effect of mitochondrial inhibitors and uncouplers on redox ratio. Initial addition of oligomycin inhibits ATP synthase, which decreases mitochondrial respiration, increases NADH that cannot be converted to NAD⁺ and hence decreases the redox ratio. FCCP is a mitochondrial uncoupler that causes protons to leak across the membrane, leading to a loss of proton gradient and hence the ability to generate ATP. Because the cell tries to restore the proton gradient, NADH is consumed, leading to increased redox ratio. Finally, Rotenone and Antimycin inhibit complexes I and III, leading to a shutdown of mitochondrial respiration and a decrease in the redox ratio.