Amiodarone-induced disruption of hamster lung and liver mitochondrial function : lack of association with thiobarbituric acid-reactive substance production

Abstract Amiodarone (AM) is an efficacious antidysrhythmic agent that is limited clinically by numerous adverse effects. Of greatest concern is AM-induced pulmonary toxicity (AIPT) due to the potential for mortality. Mitochondrial alterations and free radicals have been implicated in the etiology of AM-induced toxicities, including AIPT. Isolated hamster lung and liver mitochondria were assessed for AM-induced effects on respiration, membrane potential, and lipid peroxidation. AM (50–400 μ M) stimulated state 4 (resting) respiration at complexes I and II of tightly coupled lung mitochondria, with higher concentrations (200 and 400 μ M) resulting in a subsequent inhibition. This biphasic effect of AM (200 μ M) was also observed with isolated liver mitochondria. Only inhibition of respiration was observed with AM (50–400 μ M) in less tightly coupled lung mitochondria. Based on safranine fluorescence, 200 μ M AM decreased lung mitochondrial membrane potential ( p μ M) decrease of membrane potential was observed with liver mitochondria exposed to AM ( p μ M) in incubations lasting up to 1 h. These results indicate that lipid peroxidation, as indicated by levels of TBARS, does not play a role in AM-induced alterations in mitochondrial respiration and membrane potential.