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.