Fig. 1. Nuclear condensation and caspase activity during chronic hypoxia. (A)
Rapidly contracting neonatal cardiac myocytes were exposed to hypoxia
(PO2 <8 mmHg) in minimal essential medium
(MEM) with 5% fetal calf serum (FCS) as described previously
(Webster and Bishopric, 1992).
The medium was replaced every 12 h with fresh hypoxic medium so that the pH
was maintained at >7.2, glucose was not depleted and ATP level was
maintained at >70% control. Nuclei were stained with Hoechst 33342 and
examined microscopically as described previously
(Dougherty et al., 2002;
Webster et al., 1999). (B)
Cultures were maintained as in A, harvested as indicated, and the cells lysed
for caspase assays using a kit from Ambion Inc. (Austin, TX, USA) as described
previously (Dougherty et al.,
2002). Differences were not significant at P=0.30
(N=6). Values are means ± S.E.M.