Reactive Oxygen Species Generation by Reverse Electron Transfer at Mitochondrial Complex I Under Simulated Early...

Area of Science:

• Mitochondrial physiology
• Cardiovascular research
• Biochemistry

Background:

• Ischemic tissues accumulate succinate, leading to mitochondrial reactive oxygen species (ROS) production upon reperfusion, contributing to cell death.
• Reverse electron transfer (RET) at mitochondrial complex I (Cx-I) is implicated as a major source of ROS in reperfusion injury.

Approach:

• Investigated ROS generation in mouse cardiac mitochondria under simulated early reperfusion conditions.
• Assessed the impact of factors like high NADH, lactate, acidic pH, ATP/ADP ratios, nucleosides, and calcium on Cx-I RET and overall ROS production.

Key Points:

• Under simulated reperfusion, overall mitochondrial ROS generation was reduced compared to succinate alone.
• The contribution of Cx-I RET to ROS generation was significantly lower than previously suggested.
• Complex III (Cx-III) and other upstream sources contribute to non-RET ROS.

Conclusions:

• The role of Cx-I RET in driving pathologic ROS during reperfusion injury may be overestimated.
• Other mitochondrial ROS sources play a significant role in early reperfusion injury, necessitating further investigation.