Reexamination of respiration-impairing effect of bikaverin on isolated mitochondria

Summary  Kovac et al (1) have shown that bikaverin uncouples oxidative phosphorylation of mitochondria at 20μg/ml (52 nmol/ml) in the reaction system without magnesium (Mg²⁺). In the present study, the effects of bikaverin on mitochondrial reactions were reexamined in detail at various concentrations both in the reaction systems with and without magnesium, using isolated rat liver mitochondria and submitochondrial particles (SMP) to characterize its mode of actions to mitochondrial respiration at low concentrations (<30nmol/mg mitochondrial protein). It was concluded that bikaverin showed no uncoupling effect (no decrease in P/O ratio) at low concentrations and did it at high concentrations in consequence of disturbing the ion permeability in the mitochondrial inner membranes. At low concentrations, bikaverin repressed both NAD- and succinate-linked respirations, but did not interfere with electron transport and energy transfer systems of mitochondria.