U. Pliquett et al., DETERMINATION OF THE ELECTRIC-FIELD AND ANOMALOUS HEATING CAUSED BY EXPONENTIAL PULSES WITH ALUMINUM ELECTRODES IN ELECTROPORATION EXPERIMENTS, Bioelectrochemistry and bioenergetics, 39(1), 1996, pp. 39-53
Electroporation is well known to depend non-linearly on the magnitude
and duration of the change Delta U(t) in transmembrane voltage. In the
case of cell suspension experiments, an electric field E(e)(t) within
the electrolyte causes Delta U(t), which is is governed by both the s
ize and shape of a cell, and also by E(e)(t). It is therefore importan
t to determine the magnitude and time dependence of the electric field
to which cells are actually exposed in electroporation experiments. T
his can be significantly different from the nominal field E(n), which
is calculated by using electrode voltages and geometries alone. Throug
hout we used single, nominally exponential pulses with time constants
tau(pulse) ranging from about 0.6 to 5 ms and found that E(e) was alwa
ys less than E(n). In order to determine the actual electric field pul
se, we measured the voltage across the electrodes, the current through
the cuvette, the temperature rise of the pulsing medium, and the volt
age across two special electrodes placed within the cuvette. From thes
e measurements we calculated the field strength inside the cuvette usi
ng two different methods. In addition, we compared the measured temper
ature rise with that expected from the electrical power dissipation. I
n some cases there was much larger (''anomalous'') heating, due to int
erfacial electrochemical heat production; for one pulsing solution T-e
(t) was about 30 K larger than expected. These effects are important f
or experiments aimed at elucidating the electroporation mechanism, com
paring results obtained under different conditions, and guiding applic
ations.