Electric field pulses can induce apoptosis

Injection of electric field pulses of high in tensity (kV/cm) and short dur ation (microsecond range) into a cell suspension results in a temporary inc rease of the membrane permeability due to a reversible electric breakdown o f the cell membrane. Here we demonstrate that application of supercritical field pulses between 4.5 and 8.1 kV/cm strength and 40 mu sec duration indu ce typical features of apoptosis in Jurkat T-lymphoblasts and in HL-60 cell s including DNA fragmentation and cleavage of the poly(ADP ribose) polymera se. Apoptosis induction did not depend on the presence of any particular el ectrolyte in the extracellular medium. However, no apoptosis was observed i n solutions without a minimum amount of salt. Apoptotic DNA fragmentation w as prevented by the caspase inhibitor zVAD.