Fig. 4.

Formation of nanopores leads to phosphatidylserine externalization, cell swelling and blebbing. (a, b): Changes in Annexin V-FITC and propidium fluorescence in GH3 cells caused by a train of 5 nsEP at 7 kV/cm (a) or 14 kV/cm (b); the onset of the train is indicated by arrows. Right panels show respective DIC images (top) and superimposed Annexin V-FITC (green) and propidium (red) fluorescence at the bottom. Note immediate PS externalization without propidium uptake (a) or with minimum uptake after a more intense nsEP treatment (b). Also note swelling of nsEP-treated cells. (c) Blebbing in GH3 cells subjected to a train of 40 pulses at 4.4 kV/cm. All three panels show propidium fluorescence (red) on top of DIC images. One cell, in the top left corner, was propidium-positive already before the treatment. From left to right: immediately prior to nsEP, 1 min after it, and 10 sec after permeabilization of cells by 0.1% digitonin. Note that digitonin also caused implosion of blebs. Calibration bars: 5 µm (a, b) and 20 µm (c).