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Oxygen radicals and myocardial stunning
1Division of Cardiothoracic Surgery, University of Pennsylvania, Philadelphia.
Abstract:
There is compelling, although indirect, evidence that oxygen free radicals, generated during ischemia as well as upon reperfusion and reoxygenation of the ischemic heart, contribute to the reversible ventricular dysfunction characterized as myocardial stunning. Evidence of cell membrane damage as well as depression of sarcoplasmic reticulum and mitochondrial function with resulting calcium overload of the cell may be a result of lipid peroxidation of the cell by free radical products. Radical scavenger enzymes have been shown to greatly reduce the appearance of mRNA of a stress response protein (heat shock protein 71) in a pig heart model of stunning. The potential role for the introduction of antioxidant enzymes or stress protein in the cell is presented as a possible strategy for attenuating free radical damage during postischemic reflow.
Insights
Oxygen free radicals contribute to myocardial stunning after heart ischemia. Antioxidant enzymes may reduce this damage by preventing lipid peroxidation and calcium overload.
Area of Science:
- Cardiovascular Physiology
- Biochemistry
- Cell Biology
Background:
- Ischemia and reperfusion can generate oxygen free radicals.
- These radicals may cause myocardial stunning via cell damage and calcium overload.
- Lipid peroxidation is a suspected mechanism of radical-induced cell injury.
Purpose of the Study:
- To investigate the role of oxygen free radicals in myocardial stunning.
- To explore the potential of antioxidant strategies against ischemia-reperfusion injury.
Main Methods:
- Utilized a pig heart model of stunning.
- Assessed the impact of radical scavenger enzymes on stress response protein mRNA.
- Examined evidence of cell membrane and organelle dysfunction.
Main Results:
- Indirect evidence suggests free radicals contribute to stunning.
- Radical scavengers reduced heat shock protein 71 mRNA expression.
- Observed signs of cell membrane and organelle damage consistent with lipid peroxidation.
Conclusions:
- Oxygen free radicals are implicated in myocardial stunning.
- Antioxidant enzymes show promise in mitigating free radical damage.
- Strategies involving antioxidant enzymes or stress proteins could protect the heart during postischemic reflow.