Physiology of apoptosis

Ion fluxes and volume changes of the whole cell as well as of organelles be long to the hallmarks of apoptosis; however, the molecular mechanism regula ting these changes is only poorly characterized. Several ion channels in th e plasma membrane, in particular the N-type K+ channel, the chloride channe l cystic fibrosis conductance regulator, and an outward rectifying chloride channel, as well as the mitochondrial permeability transition pore, have b een implicated to be involved in signal transduction cascades regulating ap optosis. Furthermore, Bcl-2-like proteins have been suggested to function, at least in part, as ion channels, because they display some homology to ba cterial pore-forming toxins. In contrast to the demonstration of the involv ement of these different ion channels in apoptosis, the molecular consequen ces regulated by these ion channels, and finally triggering apoptosis, are almost completely unknown.