Komlodi 2018 J Bioenerg Biomembr
KomlΓ³di T, Geibl FF, Sassani M, Ambrus A, Tretter L (2018) Membrane potential and delta pH dependency of reverse electron transport-associated hydrogen peroxide production in brain and heart mitochondria. J Bioenerg Biomembr 10.1007/s10863-018-9766-8. |
Komlodi Timea, Geibl F Fanni, Sassani Mathilde, Ambrus Attila, Tretter Laszlo (2018) J Bioenerg Biomembr
Abstract: Succinate-driven reverse electron transport (RET) is one of the main sources of mitochondrial reactive oxygen species (mtROS) in ischemia-reperfusion injury. RET is dependent on mitochondrial membrane potential (ΞΟm) and transmembrane pH difference (ΞpH), components of the proton motive force (pmf); a decrease in ΞΟm and/or ΞpH inhibits RET. In this study we aimed to determine which component of the pmf displays the more dominant effect on RET-provoked ROS generation in isolated guinea pig brain and heart mitochondria respiring on succinate or Ξ±-glycerophosphate (Ξ±-GP). ΞΟm was detected via safranin fluorescence and a TPP+ electrode, the rate of H2O2 formation was measured by Amplex UltraRed, the intramitochondrial pH (pHin) was assessed via BCECF fluorescence. Ionophores were used to dissect the effects of the two components of pmf. The K+/H+ exchanger, nigericin lowered pHin and ΞpH, followed by a compensatory increase in ΞΟm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased ΞpH and pHin, decreased ΞΟm, which resulted in a decline in H2O2 formation. It was concluded that ΞΟm is dominant over βpH in modulating the succinate- and Ξ±-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased βpH. This phenomenon reveals that from the pH component not βpH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of ΞΟm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury. β’ Keywords: Alpha-glycerophosphate, Membrane potential, Mitochondria, Nigericin, Proton motive force, Reactive oxygen species, Reverse electron transport, Succinate, Valinomycin β’ Bioblast editor: Komlodi T β’ O2k-Network Lab: HU Budapest Tretter L
Labels: MiParea: Respiration, mt-Membrane
Stress:Oxidative stress;RONS Organism: Guinea pig Tissue;cell: Heart, Nervous system Preparation: Isolated mitochondria Enzyme: Complex I, Complex II;succinate dehydrogenase Regulation: mt-Membrane potential, pH Coupling state: LEAK Pathway: S, Gp HRR: Oxygraph-2k, O2k-Fluorometer, O2k-Protocol
Succinate pathway control state, SUIT-009 AmR mt D021, Nigericin, BEC 2020.2