Komlodi 2018 J Bioenerg Biomembr

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Publications in the MiPMap
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 50:355-365

Β» PMID: 30116920 Open Access

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 (Ξ”Οˆm) and transmembrane pH difference (Ξ”pH), components of the proton motive force (pmf); a decrease in Ξ”Οˆm and/or Ξ”pH 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). Ξ”Οˆm 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 Ξ”pH, followed by a compensatory increase in Ξ”Οˆm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased Ξ”pH and pHin, decreased Ξ”Οˆm, which resulted in a decline in H2O2 formation. It was concluded that Ξ”Οˆm is dominant over βˆ†pH in modulating the succinate- and Ξ±-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased βˆ†pH. This phenomenon reveals that from the pH component not βˆ†pH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of Ξ”Οˆm 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

Cited by

Gnaiger 2020 BEC MitoPathways
Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2. https://doi.org/10.26124/bec:2020-0002

  • Komlodi et al (2022) Hydrogen peroxide production, mitochondrial membrane potential and the coenzyme Q redox state measured at tissue normoxia and experimental hyperoxia in heart mitochondria. MitoFit Preprints 2021 (in prep)
  • KomlΓ³di et al (2022) The protonmotive force - not merely membrane potential. MitoFit Preprints 2022 (in prep)

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 

Succinate pathway control state, SUIT-009 AmR mt D021, Nigericin, BEC 2020.2, MitoFit 2021 Tissue normoxia, MitoFit 2022 pmF 

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