Studies of copper ion-induced mitochondrial swelling in vitro

Abstract

1. A study of the mode and mechanism of Cu(2+)-induced mitochondrial swelling was carried out. 2. Mitochondrial swelling curves (E(520) turbidity changes) were obtained as a function of [Cu(2+)], pH, temperature and mitochondrial protein concentration. ED(50) was approx. 70mmumoles of Cu(2+). Calculation of the activation energy from the Arrhenius equation gave a value of 22900cal./mole per degree with Q(10) 4.02. 3. No lipid peroxides were formed during swelling. 4. Changes in oxygen consumption (Clark-type electrode) were dependent on the substrate used, but revealed no increased uptake in presence of Cu(2+). 5. Cu(2+)-induced swelling was inhibited by EDTA, 8-hydroxyquinoline, cyanide, citrate, bovine serum albumin, ATP, glutamate, GSH, dithiothreitol and sucrose. Azide, Amytal, antimycin A and oligomycin had no significant effect. Potentiation of swelling was seen with ascorbate, 2,4-dinitrophenol and succinate. 6. The occurrence of different types of mitochondrial swelling and the suggestion that Cu(2+)-induced swelling is mediated through a stoicheiometric interaction with a thiol-containing membrane receptor are discussed.

Interactions of copper and thermal stress on mitochondrial bioenergetics in rainbow trout, Oncorhynchus mykiss

“…However, this shift was constrained by temperature to 200 M Cu because a higher Cu concentration (500 M) caused mild contraction instead of swelling at 30 • C. In accord with our findings, Verity and Gambell (1968) reported different patterns (biphasic and sigmoidal) of swelling dependent on the Cu dose in rat liver mitochondria. The mechanisms underlying the complex Cu-induced mitochondrial swelling kinetics observed here remain unclear but could in part be related to the composite mitochondrial structure which potentially can allow different phases of swelling particularly if accompanied by uneven temperature-induced changes in membrane permeability/fluidity.…”

“…It is also possible that Cu-induced swelling is a non-enzymatic/spontaneous reaction because these reactions also bear high Q 10 values (Elias et al, 2014). Irrespective of the underlying mechanisms, Verity and Gambell (1968) reported comparable Q 10 values (∼4) for Cu-induced swelling in rat liver mitochondria indicating that this phenomenon may be typical of mitochondria exposed to Cu. Collectively, temperature modulates Cu-induced swelling and high Cu-high temperature combination appears to impose alterations in mitochondrial membrane properties or ion fluxes that inhibit mitochondria swelling and promote contraction.…”

“…Thus, the present study including the demonstration that complex II is also inhibited by Cu (Sappal et al, 2014), suggests that Cu targets molecular components common to complex I and II. These molecular components are possibly thiols, which are prevalent in the mitochondrial ETC enzymes and are known Cu targets (Verity and Gambell, 1968;Wojtczak et al, 1996).…”

Resveratrol-sensitized UVA induced apoptosis in human keratinocytes through mitochondrial oxidative stress and pore opening

“…Therefore, oxidative stress in mitochondria induced by resveratrol and UVA possibly is the result of effects by both, copper and iron. Verity and Gambell [29] also studied the effect of copper on mitochondria in vitro. They proposed that Cu ++ induced mitochondrial swelling is mediated through a stoichiometric interaction with a thiol-containing membrane receptor.…”

Pathological mitochondrial copper overload in livers of Wilson's disease patients and related animal models

“…In a physiological context, such damage is devastating, as the IM has to be impermeable in order to sustain the transmembrane potential (ΔΨ) needed for ATP synthesis . The MPT (i.e., the irreversible mitochondrial destruction) is induced in vitro by 10–30 nmol Cu 2+ /mg mitochondrial protein, and proceeds within minutes . Preceding addition of thiol‐containing compounds like dithiothreitol (DTT) or GSH efficiently block this swelling .…”