A necessary role for cell shrinkage in apoptosis

The loss of cell volume is a fundamental and universal characteristic of pr ogrammed cell death. However, what was once thought to be a passive, second ary feature of the cell death process has now become an area of research in terest. Recent studies have integrated cell volume regulation and the movem ent of ions with the activation of apoptosis. A dramatic reduction of potas sium and sodium concentration has been shown to occur in apoptotic cells th at exhibit a shrunken morphology. Furthermore, maintaining the normal physi ological intracellular concentration of monovalent ions, particularly potas sium, inhibits the activation and activity of the death cascades. Thus, the role ions play during apoptosis is more extensive than just facilitation o f the loss of cell volume. In this article, we will review the concepts of cell Volume regulation and the loss of volume during apoptosis. Additionall y, we will underscore our current understanding of ion movement as it relat es to the activation of the cell death process. BIOCHEM PHARMACOL 56;12:154 9-1559, 1998. (C) 1998 Elsevier Science Inc.