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FIGURE 1. Hypothesizing an ischemia-apoptosis-necrosis spectrum. Coronary artery occlusion leads to ischemic changes. Annexin A5 imaging data support that ischemia is indeed equivalent to early phase of apoptosis, which is represented by death receptor upregulation, PS exteriorization, and caspase-3 activation (14,18). In cardiomyocytes, cell death by apoptosis is unlikely since reduction in blood supply depletes adenosine triphosphate and death may ensue by secondary necrosis. PS-flagged death mechanisms may be amenable to annexin A5 imaging. Pathologic states leading to sarcolemmal interruption should be detectable by antimyosin/pyrophosphate imaging (2,3).
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