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In the present study, we report the effects of extracellular medium conductivity on cell response in the context of sub-microsecond range (100 ns-900 ns) electroporation, calcium electroporation and cell size. The effects of 25 ns and microsecond range (100 μs) pulses were also covered. As a model, three different cancer cell lines of various size (C32, MCF-7/DX and MC38/0) were used and the results indicated different size-dependent susceptibility patterns to the treatment. The applied pulsed electric field (PEF) protocols revealed a significant decrease of cell viability when calcium electroporation was used. The dependence of calcium ion transport and finally the anticancer effect on the external medium conductivity was determined. It was shown that small differences in conductivity do not alter viability significantly, however, mostly affect the permeabilization. At the same, MC38/0 cell line was the least susceptible to calcium electroporation, while the C32 line the most. In all cases calcium electroporation was mostly dependent on the sensitivity of cells to electroporation and could not be effectively improved by the increase of CaCl 2 concentration from 2 mM to 5 mM. Lastly, sub-microsecond PEF stimulated aquaporin-4 and VDAC1/Porin immunoreactions in all treated cells lines, which indicated that cell water balance is affected, ions exchange is increased and release of mitochondrial products is occurrent.Electroporation is a phenomenon of pulsed electric field (PEF) initiated permeabilization of biological cell plasma membrane, which serves as a basepoint of many successful biomedical and biotechnological methodologies 1,2 . The mechanism of electroporation is dependent on cell polarization in PEF and transient charge accumulation on the cell membrane (known as transmembrane potential, TMP) 3,4 . When a threshold TMP is reached, the permeability of cell membrane is increased due to occurrence of transient hydrophilic pores 5 . It is believed that oxidative effects can be a separate mechanism responsible for the formation of pores during electroporation 6,7 , nevertheless, polarization of the cell is a primary trigger.Polarization of the cell depends on the parameters of PEF, however, also on the permittivity and conductivity of both the cells and the medium 3,8 . Therefore, the effects of extracellular medium conductivity on electroporation efficiency have been focused for decades 9-12 . Absolute majority of the scientific works focus the micro-millisecond range of pulses, while a new modality of shorter (nanosecond range) pulses was introduced and is gaining popularity 13,14 . Currently, there are two contributions 10,11 experimentally focusing the 12-102 ns range of pulses in the context of extracellular medium conductivity, while the sub-microsecond range is not covered in literature. Both papers are published by the same group Silve et al., however the upmost interest lies in the peculiar cell response to 12 ns pulses. According to these studies, the same DC3-F cell line indicated an opposite respons...

Recently, a novel contactless treatment method based on high-power pulsed electromagnetic fields (PEMF) was proposed, which results in cell membrane permeabilization effects similar to electroporation. In this work, a new PEMF generator based on multi-stage Marx circuit topology, which is capable of delivering 3.3 T, 0.19 kV/cm sub-microsecond pulses was used to permeabilize pathogenic yeast Candida albicans separately and in combination with conventional square wave electroporation (8-17 kV/cm, 100 μs). Bursts of 10, 25, and 50 PEMF pulses were used. The yeast permeabilization rate was evaluated using flow cytometric analysis and propidium iodide (PI) assay. A statistically significant (P < 0.05) combinatorial effect of electroporation and PEMF treatment was detected. Also the PEMF treatment (3.3 T, 50 pulses) resulted in up to 21% loss of yeast viability, and a dose-dependent additive effect with pulsed electric field was observed. As expected, increase of the dB/dt and subsequently the induced electric field amplitude resulted in a detectable effect solely by PEMF, which was not achievable before for yeasts in vitro.