Chinese hamster ovary cells sensitivity to localized electrical stresses

Application of an external electric field on a cell suspension induces an a lteration in the membrane structure giving free access to the cell cytoplas m. Under mild pulsation conditions, permeabilization is a reversible proces s which weakly affects cell viability while drastic electrical conditions l ead to cell death. The field pulse must be considered as a complex stress a pplied on the cell assembly. This study is a systematic investigation of th e stress effects of field strength, pulse duration and number of pulses, at given joule energy. The loss in cell viability is not related to the energ y delivered to the system. At a given joule energy, a strong field during a short cumulated pulse duration affects more viability than using a weak fi eld associated with a long cumulated pulsation. At a given field strength a nd for a given cumulated pulse duration an accumulation of short pulses is also observed to be very damaging for cells. A control by the delay between the pulses suggests a memory effect. The field effect appears also to be v ectorial in Line with the known asymmetry of the membrane organization. The se results suggest that processes at a cellular level are involved, either an activation of cell death or damage in cellular functions. (C) 1999 Elsev ier Science S.A. All rights reserved.