Chronic hypoxia induces apoptosis in cardiac myocytes: A possible role forBcl-2-like proteins

The effect of prolonged hypoxia as well as the molecular mechanisms on card iac cell death is not well established. A possible role of Bcl-2 and Bax in hypoxia-induced apoptosis in different cell types has been proposed. Here we demonstrate the effect of hypoxia on the induction of apoptosis and the expression of Bcl-2-like proteins in vivo and in vitro. Hearts from rats ex posed to chronic hypoxia (n = 4) showed an increased rate of apoptosis comp ared to normoxic hearts (n = 4). The induction of apoptosis in hypoxic hear ts correlated with a significant decrease of Bcl-2 protein level, whereas B ax protein expression was increased. Exposure of isolated neonatal rat card iac myocytes to hypoxia also resulted in a significant increase in apoptosi s. However, Bcl-2 and Bax protein levels essentially remained unchanged. Ou r results may suggest a different molecular mechanism of hypoxia-induced ap optosis in vivo and in vitro. (C) 2001 Academic Press.