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Membrane potential and delta pH dependency of reverse electron transport-associated hydrogen peroxide production in brain and heart mitochondria
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 (Δψ m ) and transmembrane pH difference (ΔpH), components of the proton motive force ( pm...
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Published in: | Journal of bioenergetics and biomembranes 2018-10, Vol.50 (5), p.355-365 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | 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 (Δψ
m
) and transmembrane pH difference (ΔpH), components of the proton motive force (
pmf
); a decrease in Δψ
m
and/or ΔpH 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 α-glycerophosphate (α-GP). Δψ
m
was detected via safranin fluorescence and a TPP
+
electrode, the rate of H
2
O
2
formation was measured by Amplex UltraRed, the intramitochondrial pH (pH
in
) was assessed via BCECF fluorescence. Ionophores were used to dissect the effects of the two components of
pmf
. The K
+
/H
+
exchanger, nigericin lowered pH
in
and ΔpH, followed by a compensatory increase in Δψ
m
that led to an augmented H
2
O
2
production. Valinomycin, a K
+
ionophore, at low [K
+
] increased ΔpH and pH
in
, decreased Δψ
m
, which resulted in a decline in H
2
O
2
formation. It was concluded that Δψ
m
is dominant over ∆pH in modulating the succinate- and α-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H
2
O
2
release and a decreased ∆pH. This phenomenon reveals that from the pH component not ∆pH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of Δψ
m
might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury. |
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ISSN: | 0145-479X 1573-6881 |
DOI: | 10.1007/s10863-018-9766-8 |