Effects of the membrane potential upon the Ca2+‐ and cumene hydroperoxide‐induced permeabilization of the inner mitochondrial membrane

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Abstract
A protonophore‐induced ΔΨ decrease in a 180‐140 mV range causes an increase in the lag‐period of Ca2+‐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 Ca2+. 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.