Induction of the mitochondrial permeability transition (MPT) by micromolar iron: Liberation of calcium is more important than NAD(P)H oxidation

► 20 μM Fe(II) induces mitochondrial permeability transition in isolated mitochondria. ► Iron causes NAD(P)H oxidation but this is only marginally involved in MPT induction. ► Small fraction of added iron was imported by calcium uniporter. ► MPT propagation continues through calcium release/reuptake. ► The effect of iron depends on its ability to displace calcium from residual EDTA.