In vitro effect of melatonin on oxygen consumption in liver mitochondria of rats.

Reyes-Toso C, Ricci C, de Mignone I, Reyes P, Linares L, Albornoz L, Cardinali D, Zaninovich A.
  Vol. 24 (5) 2003 Neuro endocrinology letters Journal Article   2003; 24(5): 341-344 PubMed PMID:  14647009    Citation  Keywords:  3-Hydroxybutyric Acid:metabolism, Animals, Antioxidants:pharmacology, In Vitro Techniques, Malates:metabolism, Male, Melatonin:pharmacology, Mitochondria, Liver:drug effects, Oxygen Consumption:drug effects, Rats, Rats, Wistar, Succinic Acid:metabolism,.   

OBJECTIVE: To examine the in vitro effect of melatonin on rat mitochondrial liver respiration.

METHODS: Oxygen consumption by liver mitochondria was measured polarographically in the presence of one of the following Krebs' cycle substrates: Lsuccinate, DL-3- beta-hydroxybutyrate or L-malate. Respiratory velocities at rest (state 4) and during rapid respiration in the presence of substrate and adenosine diphosphate (state 3) were measured in the presence of 10 (-9)-10(-3) M concentrations of melatonin.

RESULTS: In vitro melatonin (10(-7)-10(-3) M) reduced state 3 mitochondrial respiration. Basal, state 4 respiration was not affected by melatonin. Consequently, control respiratory index (i.e., the ratio of state 3 to state 4 respiration) was inhibited by melatonin with a threshold at 10(-7) M concentration.

CONCLUSION: The ability of melatonin to curtail acutely the stimulation of oxygen consumption in liver mitochondria may protect the mitochondria from excessive oxidative damage.