The Effects of Intense Submicrosecond Electrical Pulses on Cells

Abstract

A simple electrical model for living cells predicts an increasing probability for electric field interactions with intracellular substructures of both prokaryotic and eukaryotic cells when the electric pulse duration is reduced into the sub-microsecond range. The validity of this hypothesis was verified experimentally by applying electrical pulses (durations 100 micros-60 ns, electric field intensities 3-150 kV/cm) to Jurkat cells suspended in physiologic buffer containing propidium iodide. Effects on Jurkat cells were assessed by means of temporally resolved fluorescence and light microscopy. For the longest applied pulses, immediate uptake of propidium iodide occurred consistent with electroporation as the cause of increased surface membrane permeability. For nanosecond pulses, more delayed propidium iodide uptake occurred with significantly later uptake of propidium iodide occurring after 60 ns pulses compared to 300 ns pulses. Cellular swelling occurred rapidly following 300 ns pulses, but was minimal following 60 ns pulses. These data indicate that submicrosecond pulses achieve temporally distinct effects on living cells compared to microsecond pulses. The longer pulses result in rapid permeability changes in the surface membrane that are relatively homogeneous across the cell population, consistent with electroporation, while shorter pulses cause surface membrane permeability changes that are temporally delayed and heterogeneous in their magnitude.

Tissue Damage by Pulsed Electrical Stimulation

“…To eliminate variability from the dynamics of PI uptake with the cells [28], the total exposure time was defined as 5 min and the number of pulses within that window was adjusted by varying the pulse repetition rate. Data in Fig.…”

Stimulation of Capacitative Calcium Entry in HL-60 Cells by Nanosecond Pulsed Electric Fields

“…An aliquot of HL-60 cell suspension was loaded into a space between metal electrodes affixed to a slide for real time monitoring of calcium transients. A description of this nsPEF apparatus can be found in the article by Deng et al (31). To analyze the cell response, Merlin software (PerkinElmer Life Sciences) was used to detect changes in gray scale of the selected cell areas, and we compared these changes to a background region.…”

Nanosecond electric pulses penetrate the nucleus and enhance speckle formation

“…To better understand the mechanism involved, mathematical models for the cellular electropermeabilization due to nsPEFs have been developed [3,4]. The resulting changes in cellular structures and functions differ significantly from traditional electroporation [microseconod to millisecond pulsed electric fields (PEFs)] [1,5,6]. Increased permeabilization of the plasma membrane, typically demonstrated by measuring propidium iodide (PI) uptake, due to nsPEFs was delayed compared to traditional electroporation [5,6], indicating that it was an indirect effect.…”

“…The resulting changes in cellular structures and functions differ significantly from traditional electroporation [microseconod to millisecond pulsed electric fields (PEFs)] [1,5,6]. Increased permeabilization of the plasma membrane, typically demonstrated by measuring propidium iodide (PI) uptake, due to nsPEFs was delayed compared to traditional electroporation [5,6], indicating that it was an indirect effect. These nsPEFs induced cellular calcium release [7,8] and apoptosis in cells [9,10] or tumors [11,12].…”