The number of molecules taken up by electroporated cells: quantitative
Bartoletti DC; Harrison GI; Weaver JC FEBS Lett (EUH), 1989 Oct 9; 256 (1-2): 4-10
Fluorescent and fluorescent-labeled molecules were used with
calibrated flow cytometric fluorescence measurements of
electrically pulsed cells (intact yeast: Saccharomyces
cerevisiae) to demonstrate a method for determining the net
number of molecules transported into electroporated cells.
For the conditions used, a single pulse of width 50
microseconds and magnitude 8.0 +/- 0.5 kV/cm resulted in an
average net molecular uptake which is large, n = 1.4 x 10(5)
molecules of 70 kDa FITC-dextran (supplied extracellular
concentration of 500 microM), and n = 1.0 x 10(8) molecules
of 660 Da propidium iodide (PI; 80 microM). Both molecules
were present in pulsed cells at less than equilibrium
values, consistent with a transient uptake mechanism.
Intracellular FITC-dextran is present in soluble form, while
PI is predominantly bound to nucleic acids. A broad,
statistically significant distribution of molecular uptake
was also observed. Such quantitative determinations should
be important for guiding applications of electroporation,
and for testing models of electroporation mechanisms.
Further, the use of PI, which is well established as a
membrane exclusion dye, provides additional support for the
interpretation that both PI and FITC-dextran were
internalized as a result of an electrical pulse.