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Updated: Sep 3, 2026
Determination of Mitochondrial Membrane Potential and Reactive Oxygen Species in Live Rat Cortical Neurons
Published on: May 23, 2011
Mitochondrial generation of reactive oxygen species after brain ischemia in the rat
1Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
Background And Purpose:
Brain mitochondria have a substantial capacity to generate reactive oxygen species after ischemia when the components of the respiratory chain are reduced and molecular oxygen is present. We tested the hypothesis that brain mitochondria in vivo produce reactive oxygen species after ischemia/reperfusion (IR) in rats at a rate sufficient to escape endogenous antioxidant defenses.
Methods:
Ischemia-dependent production of hydroxyl radical in the hippocampus of the anesthetized rat was monitored with the use of intracerebral microdialysis. Transient global ischemia was produced by bilateral carotid artery occlusion and hemorrhagic hypotension to a mean arterial pressure of 35 mm Hg for 15 minutes followed by reperfusion for 60 minutes. Salicylic acid was infused into the hippocampus during the experiments, and changes in the recovery of its hydroxylated product, 2,3-dihydroxybenzoic acid (2,3-DHBA), were used to assess the effects of inhibitors of mitochondrial complex I on formation of hydroxyl radical during IR. Hydroxylation data from control groups of animals were compared with data from animals undergoing IR during treatment with either a mitochondrial complex I inhibitor alone or the inhibitor plus succinic acid.
Results:
Transient ischemia led to a fivefold increase in the recovery of 2,3-DHBA by microdialysis after 1 hour relative to control animals (P < .05). Inhibition of mitochondrial complex I prevented 2,3-DHBA formation after IR; this effect could be reversed by infusion of succinic acid by microdialysis during IR.
Conclusions:
The data indicate that reactive oxygen species generated by mitochondrial electron transport escape cellular antioxidant defenses and promote highly damaging hydroxyl radical activity after transient brain ischemia in the rat.
Insights
Brain mitochondria generate reactive oxygen species during ischemia/reperfusion, overwhelming antioxidant defenses and causing hydroxyl radical damage in rats. This study highlights mitochondrial dysfunction as a key factor in brain injury.
Area of Science:
- Neuroscience
- Mitochondrial Biology
- Biochemistry
Background:
- Brain mitochondria generate reactive oxygen species (ROS) post-ischemia.
- Mitochondrial respiratory chain components are reduced during ischemia.
- Oxygen availability promotes ROS production.
Purpose of the Study:
- To test if brain mitochondria produce ROS in vivo at a rate exceeding antioxidant defenses after ischemia/reperfusion (IR).
- To investigate the role of mitochondrial complex I in ROS generation during IR.
Main Methods:
- Intracerebral microdialysis in rats to monitor hydroxyl radical production in the hippocampus.
- Transient global ischemia induced by carotid artery occlusion and hypotension.
- Assessment of hydroxyl radical formation using salicylic acid hydroxylation (2,3-dihydroxybenzoic acid).
- Inhibition of mitochondrial complex I and reversal with succinic acid.
Main Results:
- Ischemia/reperfusion caused a fivefold increase in hydroxyl radical product (2,3-DHBA).
- Mitochondrial complex I inhibition abolished 2,3-DHBA formation.
- Succinic acid infusion reversed the inhibitory effect of complex I blockade.
Conclusions:
- Mitochondrial electron transport generates ROS that escape cellular antioxidant defenses.
- These ROS promote damaging hydroxyl radical activity after transient brain ischemia.
- Mitochondrial dysfunction is a critical contributor to ischemic brain injury.
