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


CONCLUSIONS
The ability of melatonin to curtail acutely the stimulation of oxygen consumption in liver mitochondria may protect the mitochondria from excessive oxidative damage.
Reyes-Toso
Carlos F
CF
Departamento de Fisiologia and Hospital de Clinicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
Ricci
Conrado R
CR
de Mignone
Inés R
IR
Reyes
Patricia
P
Linares
Laura M
LM
Albornoz
Liliana E
LE
Cardinali
Daniel P
DP
Zaninovich
Angel
A
D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D066298:In Vitro Techniques; D008293:Malates / Q000378:metabolism; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D019802:Succinic Acid / Q000378:metabolism
D000975:Antioxidants; D008293:Malates; C030298:malic acid; D019802:Succinic Acid; D008550:Melatonin; D020155:3-Hydroxybutyric Acid