Long-lived macropinocytosis takes place in electropermeabilized mammalian cells

Electropermeabilization is a technique which allows free access of molecules 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 electric field intensity but long time duration (ms time range), all the pulsed cells become permeable to macromolecules. By loading beta-galactosidase the electro-transferred activity in the cells is maintained over 24 hours. Transfer mediated during the pulse occurs by free diffusion into the cytoplasm, while post pulse transfer takes place by a different pathway. When added a few minutes after application of the electric field, the enzyme enters the cell via a macropinocytosis-like process. This is a new long-term effect of the electric field pulse on the membrane.