Plasma Membrane Voltage Changes during Nanosecond Pulsed Electric Field Exposure

Abstract

The change in the membrane potential of Jurkat cells in response to nanosecond pulsed electric fields was studied for pulses with a duration of 60 ns and maximum field strengths of approximately 100 kV/cm (100 V/cell diameter). Membranes of Jurkat cells were stained with a fast voltage-sensitive dye, ANNINE-6, which has a subnanosecond voltage response time. A temporal resolution of 5 ns was achieved by the excitation of this dye with a tunable laser pulse. The laser pulse was synchronized with the applied electric field to record images at times before, during, and after exposure. When exposing the Jurkat cells to a pulse, the voltage across the membrane at the anodic pole of the cell reached values of 1.6 V after 15 ns, almost twice the voltage level generally required for electroporation. Voltages across the membrane on the side facing the cathode reached values of only 0.6 V in the same time period, indicating a strong asymmetry in conduction mechanisms in the membranes of the two opposite cell hemispheres. This small voltage drop of 0.6-1.6 V across the plasma membrane demonstrates that nearly the entire imposed electric field of 10 V/mum penetrates into the interior of the cell and every organelle.

Electroporation of Asymmetric Phospholipid Membranes

“…7 Recently, the so-called supra-electroporation that employs nanosecond-scale pulses of large magnitude has emerged, 8 so that electric-field-induced permeabilization of organelle membranes has now become possible. 9 In MD simulation studies, an electric field is applied to a lipid membrane either as an external force added to all charged atoms in the system 3,4,10−12 or through a transmembrane ionic charge imbalance.…”

The Role of Electrochemotherapy in the Treatment of Malignant Melanoma

“…These higher electric fields increase the possibility of producing non resealable pores, thus producing the effect of irreversible electroporation, and consequently allowing the cells to lose their cytoplasm with concomitant cell death. This principle is being used for tumor ablation, palliation or both 43, www.intechopen.com [107][108][109] . However in the treatment of melanoma, the advantages of these higher electric fields are not immediately evident.…”

Time dependence of electric field effects on cell membranes. A review for a critical selection of pulse duration for therapeutical applications

“…A fast charging capacitive effect is present. 50 Two membrane capacitances, C 1 for the outer cell plasma membrane and C 2 for the inner organelle membrane, are being charged by currents from the exter- 52 It results a charging of the organelle capacitance. As the size of the organelle is very small and the conductivity of the cytoplasm is higher than that of the external buffer, the charging time of the organelle capacitor is much faster than that of the plasma membrane capacitor.…”

“…52 As soon as the plasma membrane is electropermeabilized, it is short circuited and only a fraction of the external field remains present on the organelles. 50,51 Another consequence of ultrashort pulses is the induction of an electrodeformation of the cell (electrostretching). The magnitude of this stress is high under low conductivities conditions.…”