Size of the pores created by an electric pulse: Microsecond vs millisecond pulses

• Published in: Biochimica et biophysica acta 2012-12, Vol.1818 (12), p.3032-3039
• Main Authors: Saulis, Gintautas, Saulė, Rita
• Format: Article
• Language: English
• Subjects: Animals; Bleomycin - pharmacology; Cell Line, Tumor; Cell Membrane - ultrastructure; Cell Membrane Permeability; CHO Cells; Cricetinae; Electricity; Electropermeabilization; Electroporation; Erythrocyte Membrane - ultrastructure; Erythrocytes - drug effects; Erythrocytes - ultrastructure; Human erythrocytes; Humans; Mice; Mouse hepatoma; Sucrose - pharmacology
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2012.06.018

Here, the sizes of the pores created by square-wave electric pulses with the duration of 100μs and 2ms are compared for pulses with the amplitudes close to the threshold of electroporation. Experiments were carried out with three types of cells: mouse hepatoma MH-22A cells, Chinese hamster ovary (CHO) cells, and human erythrocytes. In the case of a short pulse (square-wave with the duration of 100μs or exponential with the time constant of 22μs), in the large portion (30–60%) of electroporated (permeable to potassium ions) cells, an electric pulse created only the pores, which were smaller than the molecule of bleomycin (molecular mass of 1450Da, r≈0.8nm) or sucrose (molecular mass of 342.3Da, radius—0.44–0.52nm). In the case of a long 2‐ms duration pulse, in almost all cells, which were electroporated, there were the pores larger than the molecules of bleomycin and/or sucrose. Kinetics of pore resealing depended on the pulse duration and was faster after the shorter pulse. After a short 100-μs duration pulse, the disappearance of the pores permeable to bleomycin was completed after 6–7min at 24–26°C, while after a long 2-ms duration pulse, this process was slower and lasted 15–20min. Thus, it can be concluded that a short 100-μs duration pulse created smaller pores than the longer 2-ms duration pulse. This could be attributed to the time inadequacy for pores to grow and expand during the pulse, in the case of short pulses. Comparison of the sizes of the pores created by square-wave electric pulses with the duration of 100μs and 2ms for pulses with the amplitudes close to the threshold of electroporation shows that a short 100μs-duration pulse creates smaller pores than the longer 2ms-duration pulse. [Display omitted] ► Sizes of pores created by 100μs and 2ms-duration electric pulses are compared. ► Short 100‐μs-duration pulse created smaller pores than longer 2ms-duration pulse. ► Membrane impermeability for bleomycin was restored faster after 100μs pulse.