The permeability transition pore induced under anaerobic conditions in mitochondria energized with ATP

Abstract

The role of oxygen in the induction of mitochondrial permeability transitions was studied. Oxygen consumption, swelling, membrane potential and calcium transport were recorded simultaneously in isolated rat liver mitochondria. Oxygen depletion was accomplished by saturating the medium with N P and allowing either mitochondrial respiration or glucose/ glucose oxidase to consume the residual oxygen. Upon anaerobiosis, mitochondria were supplemented with 500 W WM ATP to support succinate-driven membrane potential. Under these conditions, 100 W WM Ca 2+ induced cyclosporin A-sensitive permeability transitions. To eliminate the possible inhibition of permeability transition by high concentrations of adenine nucleotides, anaerobic mitochondria were also energized by the combination of 20 W WM ADP and phosphoenolpyruvate/pyruvate kinase. These mitochondria also underwent Ca 2+ -induced permeability transition. Under both of these conditions, namely the addition of ATP as a single or through actions of pyruvate kinase, the respiratory components were totally reduced. Thus, oxygen is not a necessary factor for mitochondria to undergo permeability transitions.z 1998 Federation of European Biochemical Societies.

Testing hypotheses of aging in long-lived mice of the genus Peromyscus: association between longevity and mitochondrial stress resistance, ROS detoxification pathways, and DNA repair efficiency

“…The comparison was based on physiological responses of mitochondria of these species to sequential loads of Ca 2+ (in vitro model of Ca 2+ oscillations). A standard experimental model of supplementing isolated mouse liver mitochondria with optimal (5 mM) amounts of succinate (the respiratory substrate for complex II) in the presence of rotenone (respiratory complex I inhibitor) was used (Krasnikov et al , 2005Kuzminova et al 1998). Our results showed no difference in basal oxygen uptake, Ca 2+ retention, ΔΨ maintenance or volume change between P. leucopus and M. musculus liver mitochondria (Fig.…”

“…We also compared ΔΨ changes induced by Ca 2+ loading for both P. leucopus and M. musculus. Data were collected for each time Ca 2+ was introduced (Krasnikov et al , 2005Kuzminova et al 1998). a-d O 2 uptake, Ca 2+ flux, ΔΨ, and swelling (as reflected by changes in optical density), respectively.…”

“…Black traces P. leucopus, red traces M. musculus (strain C57BL/6). The incubation medium contained 300 mM sucrose, 5 mM Hepes, 1 mM KH 2 PO 4 , and 5 mM succinate, pH 7.4 according to previously described methods (Krasnikov et al , 2005Kuzminova et al 1998). Addition of MLM (1 mg/ml) was followed by addition of rotenone (1 μM).…”

Reactive oxygen and nitrogen species: Friends or foes?

“…On isolated mitochondria, we succeeded in demonstration that MPT induction by calcium ions takes place even under very low partial oxygen pressure [42,43]. From another side, using rat cardiac myocyte we observed that ROS can induce MPT in situ [30].…”

“…One of the most possible damaging conse quences of the MPT induction is excessive mitochondri al ROS generation, which we called ROS induced ROS release [43] representing a cascade of accelerated genera tion of ROS by mitochondria with still unclear mecha nism.…”