Relationship between membrane potential and respiration rate in isolated liver mitochondria from rats fed an energy dense diet.

We studied the relationship between membrane potential and respiration rate in isolated liver mitochondria from rats fed an energy dense diet. We conceptually divided the system into blocks of reactions that produced or consumed mitochondrial membrane potential and then measured the kinetic response of these blocks of reactions to this potential using NAD-linked and FAD-linked substrates. We show that decreased respiration rate with an NAD-linked substrate is accounted for by decreased kinetic response of the substrate oxidation pathway to the potential. No variation in the kinetic response of the above blocks of reactions to the potential was found using an FAD-linked substrate. These results indicate that FAD-linked and NAD-linked pathways are differently affected in rats fed an energy dense diet.