Fig. 2. Activation of programmed death by waste metabolites under chronic hypoxia. (A,B) Parallel cultures of cardiac myocytes were exposed to hypoxia. In A, the media was replaced with fresh hypoxic medium every 6 h. In B, the media was not replaced. Cultures were harvested at the indicated times and processed for DNA fragmentation. (C) Intracellular ATP, medium glucose and [pH]o were measured in parallel cultures (Webster et al., 1999); results are means of three separate experiments; squares represent results from cultures with media replacement; open circles show results without media replacement; filled circles represent the 72 h aerobic control. (D–F) Typical fields of myocytes stained with Hoechst 33342 and anti--MHC antibody (Webster et al., 1999). 1G Quantitations of Hoechst-stained condensed nuclei were as described in Webster et al. (1999. Results are representative of at least three experiments.