A necessary role for reduced intracellular potassium during the DNA degradation phase of apoptosis.

Apoptosis is a highly organized mechanism that allows specific cells to die in a controlled manner. Apoptosis can be induced by a variety of agents in a great number of cell types, but cell shrinkage and discrete chromatin cleavage remain common components of apoptosis that is manifested by constitutive enzymes. Despite intensive investigation, the actual event or events that signal this cell death process have not been completely identified. Because of their ability to effect a great number of cellular enzymes simultaneously, we have hypothesized that ions in high concentration (150 mM) in living cells may act as a repressor of apoptotic effectors. In this manuscript we review data that shows that DNA degradation only occurs in the shrunken population of lymphocytes treated with glucocorticoid, shrunken cells loose K+ and become hypotonic, and physiological concentrations on K+ inhibit nuclease activity irrespective of proteins. Together, these data suggest that the reduction in potassium levels appears necessary for the DNA degradation that occurs during apoptosis.