Komlodi 2018 J Bioenerg Biomembr: Difference between revisions
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|journal=J Bioenerg Biomembr | |journal=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 (ฮฯm) and transmembrane pH difference (ฮpH), components of the proton motive force (pmf); a decrease in ฮฯm and/or ฮpH 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 ฮฑ-glycerophosphate (ฮฑ-GP). ฮฯm was detected via safranin fluorescence and a TPP+ electrode, the rate of | |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 (ฮฯm) and transmembrane pH difference (ฮpH), components of the proton motive force (pmf); a decrease in ฮฯm and/or ฮpH 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 ฮฑ-glycerophosphate (ฮฑ-GP). ฮฯm was detected via safranin fluorescence and a TPP+ electrode, the rate of H<sub>2</sub>O<sub>2</sub> 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<sup>+</sup>/H<sup>+</sup> exchanger, nigericin lowered pHin and ฮpH, followed by a compensatory increase in ฮฯm that led to an augmented H<sub>2</sub>O<sub>2</sub> production. Valinomycin, a K<sup>+</sup> ionophore, at low [K<sup>+</sup>] increased ฮpH and pHin, decreased ฮฯm, which resulted in a decline in H<sub>2</sub>O<sub>2</sub> formation. It was concluded that ฮฯm is dominant over โpH in modulating the succinate- and ฮฑ-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H<sub>2</sub>O<sub>2</sub> release and a decreased โpH. This phenomenon reveals that from the pH component not โpH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of ฮฯm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury. | ||
|keywords=Alpha-glycerophosphate | |keywords=Alpha-glycerophosphate, Membrane potential, Mitochondria, Nigericin, Proton motive force, Reactive oxygen species, Reverse electron transport, Succinate, Valinomycin | ||
|editor=[[Komlodi T]], | |editor=[[Komlodi T]], | ||
|mipnetlab=HU Budapestย Tretter L | |mipnetlab=HU Budapestย Tretter L | ||
Revision as of 15:09, 11 September 2018
| Komlรณdi 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 T, Geibl FF, Sassani M, Ambrus A, Tretter L (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 (ฮฯm) and transmembrane pH difference (ฮpH), components of the proton motive force (pmf); a decrease in ฮฯm and/or ฮpH 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 ฮฑ-glycerophosphate (ฮฑ-GP). ฮฯm 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 ฮpH, followed by a compensatory increase in ฮฯm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased ฮpH and pHin, decreased ฮฯm, which resulted in a decline in H2O2 formation. It was concluded that ฮฯm is dominant over โpH in modulating the succinate- and ฮฑ-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased โpH. This phenomenon reveals that from the pH component not โpH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of ฮฯm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury. โข Keywords: Alpha-glycerophosphate, Membrane potential, Mitochondria, Nigericin, Proton motive force, Reactive oxygen species, Reverse electron transport, Succinate, Valinomycin โข Bioblast editor: Komlodi T โข 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
