Background

Observations in humans have raised the possibility that idiopathic dilated cardiomyopathy is characterized by myocyte cell loss and cell proliferation, which contribute to wall thinning and chamber dilation. Moreover, the mechanism of myocyte cell death in this patient population has been unclear. Because rapid ventricular pacing in dogs leads to a dilated myopathy that mimics the idiopathic form in man, this animal model was used to demonstrate whether myocyte nuclear mitotic division and programmed myocyte cell death occur in this setting. Additionally, the expression of proliferating cell nuclear antigen (PCNA) and Fas protein in myocytes was examined as a molecular indicator of the activation of the cell cycle and apoptotic cell death, respectively.