Reperfusion injury after ischemia is mediated primarily by which mechanism?
- A Burst generation of reactive oxygen species from xanthine oxidase and mitochondria ✓
- B Persistent ATP depletion continuing after restoration of blood flow
- C Complement activation by necrotic debris before reperfusion
- D Calcium influx from extracellular space during ischemia
Correct answer: A. Burst generation of reactive oxygen species from xanthine oxidase and mitochondria
Explanation
Reperfusion injury is driven by a burst of reactive oxygen species (ROS) generated when oxygen is suddenly reintroduced. Xanthine oxidase (activated during ischemia by conversion of xanthine dehydrogenase) uses oxygen to generate superoxide, and mitochondria produce ROS as electron transport resumes abnormally. This ROS burst, along with calcium overload and neutrophil recruitment, extends cell injury beyond that caused by ischemia alone.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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