LONG-LIVED MACROPINOCYTOSIS TAKES PLACE IN ELECTROPERMEABILIZED MAMMALIAN-CELLS

Electropermeabilization is a technique which allows free access of mol ecules to cytosol. In the present study, we report on results dealing with the penetration of macromolecules. Under electric conditions that allow maintenance of cell viability at a high level, i.e.,at low elec tric field intensity but long time duration (ms time range), all the p ulsed cells become permeable to macromolecules. By loading beta-galact osidase the electro-transfered activity in the cells is maintained ove r 24 hours. Transfer mediated during the pulse occurs by free diffusio n into the cytoplasm, while post pulse transfer takes place by a diffe rent pathway. When added a few minutes after application of the electr ic field, the enzyme enters the cell via a macropinocytosis-like proce ss. This is a new long-term effect of the electric field pulse on the membrane. (C) 1995 Academic Press, Inc.