The role of apoptosis in myocardial ischemia: a critical appraisal

Abstract

The role of apoptosis in cardiac ischemia is not clarified yet. Own data show that suicidal cell death is apparently not important in global ischemia where it only affects a small number of myocytes (8 %) while the majority of cells, i.e. 92 % die by oncosis. In acute regional ischemia it is most probably not a decisive factor. However, more solid data are needed to justify this statement. Human hibernating myocardium shows an activation of the apoptotic cascade, i.e., apoptosis might contribute to cell loss in this pathophysiological situation of multiple ischemic episodes. Manifold unresolved issues contribute to problems in determining the role of apoptosis in ischemia. These include 1) Uncertainty of the duration of the apoptotic cascade from activation of death receptors at the cellular membrane until DNA fragmentation occurs, 2) The role of the mitochondrial pathway, 3) The mode of removal of myocytes after cell death has occurred, 4) Technical problems such as specificity of the TUNEL method, detection of low abundance proteins such as activated caspases or cytochrome C, statistical considerations. These issues and many others should be clarified before any definite conclusion as to the role of apoptosis in ischemia may be drawn.