Effects of the membrane potential upon the Ca 2+- and cumene hydroperoxide-induced permeabilization of the inner mitochondrial membrane

Abstract

A protonophore-induced ΔΨ decrease in a 180-140 mV range causes an increase in the lag-period of Ca 2+-induced mitochondrial permeabilization but has little effect on the cumene hydroperoxide-induced permeability transition of mitochondria. Suppression of the non-specific permeability induction seems to be mediated by an increase in [ADP] in the mitochondrial matrix. A further decrease in ΔΨ leads to additional suppression of the non-specific permeability as a result of a partial ruthenium red-sensitive efflux of the previously accumulated Ca 2+. On the other hand, complete dissipation of ΔΨ causes immediate induction of the non-specific permeability. It is concluded that only complete dissipation of ΔΨ caused by H + leakages may act as a trigger for non-specific permeability induction.