Reperfusion injury following myocardial ischemia is mediated primarily by which mechanism?
- A Burst generation of reactive oxygen species and mitochondrial permeability transition pore opening ✓
- B Sudden restoration of ATP causing osmotic cell lysis
- C Immediate complement activation through the classical pathway
- D Rapid intracellular pH normalization causing calcium overload through Na+/H+ exchanger reversal
Correct answer: A. Burst generation of reactive oxygen species and mitochondrial permeability transition pore opening
Explanation
Reperfusion injury is primarily mediated by a burst of ROS (superoxide, hydroxyl radical) generated by xanthine oxidase, NADPH oxidase, and damaged mitochondria upon oxygen reintroduction. ROS trigger the mitochondrial permeability transition pore (mPTP) opening, causing mitochondrial swelling and apoptosis/necrosis. Both ROS and calcium overload contribute, but ROS-driven mPTP opening is the central mechanism.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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