Expression of bcl-2 Protein, an Inhibitor of Apoptosis, and Bax, an Accelerator of Apoptosis, in Ventricular Myocytes of Human Hearts With Myocardial Infarction

Background In general, myocyte death in myocardial infarctions (MIs) is attributed to necrosis, but recently the involvement of apoptosis has been suggested. The ratio of bcl-2 protein, an inhibitor of apoptosis, to Bax protein, an inducer of apoptosis, determines survival or death after an apoptotic stimulus. We speculated that bcl-2 or Bax expression is induced by ischemia and that it may be related to myocyte death in human hearts. Methods and Results We studied immunohistochemically 37 autopsied human hearts (acute MI, n=15; old MI, n=12; normal hearts as a control, n=10) with the use of bcl-2 and Bax antibodies. There were no myocytes with positive bcl-2 immunoreactivity in the controls or hearts with old MI. However, myocytes with positive bcl-2 immunoreactivity were seen in 9 of 15 hearts (60%) with acute MI, in that it was localized only in salvaged areas surrounding the infarcted tissues. Myocytes with slightly positive Bax immunoreactivity were observed in the control hearts. In the salvaged myo...