The effect of ferric iron complex on isolated rat liver mitochondria. I. Respiratory and electrochemical responses.

Addition of iron(III)-gluconate complex to isolated rat liver mitochondria resulted in an increased iron content of mitochondria. Iron was accumulated through a relatively fast process (maximal uptake in less than 2 min incubation) by an energy-independent mechanism. The in vitro iron overload of mitochondria was associated with enhancement in the oxygen consumption, which was due to the induction of lipoperoxidative processes catalyzed by iron. It was found that a concentration of iron as low as 0.1 mM elicits a consistent production of malondialdehyde in mitochondria. Concomitant with the induction of lipoperoxidation a progressive fall in the mitochondrial membrane potential was observed. The occurrence of energy-consuming processes as a consequence of iron addition, and particularly the enhancement of endogenous Ca2+ cycling across the membrane, was suggested as the cause of the membrane potential drop.