Cellular adaptive responses to low oxygen tension: apoptosis and resistance.

Oxygen plays such a critical role in the central nervous system that a specialized mechanism of oxygen delivery to neurons is required. Reduced oxygen tension, or hypoxia, may have severe detrimental effects on neuronal cells. Several studies suggest that hypoxia can induce cellular adaptive responses that overcome apoptotic signals in order to minimize hypoxic injury or damage. Adaptive responses of neuronal cells to hypoxia may involve activation of various ion channels, as well as induction of specific gene expression. For example, ATP sensitive K+ channels are activated by hypoxia in selective neuronal cells, and may play a role in cell survival during hypoxia/anoxia. Additionally, hypoxia-induced c-Jun, bFGF and NGF expression appear to be associated with prevention (or delay) of neuronal cell apoptosis. In this paper, these adaptive responses to hypoxia in neuronal cells are discussed to examine the possible role of hypoxia in pathophysiology of diseases.