title: Transient features in nanosecond pulsed electric fields differentially modulate mitochondria and viability.
abstract: It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs), determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0-80 kV/cm) and short (15 ns) or long (150 ns) rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE) to determine mitochondria membrane potentials (ΔΨm). Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death.
authors.affiliation: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia, United States of America. sbeebe@odu.edu
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Beebe
authors.forename: Yeong-Jer
authors.initials: YJ
authors.lastname: Chen
authors.forename: Nova M
authors.initials: NM
authors.lastname: Sain
authors.forename: Karl H
authors.initials: KH
authors.lastname: Schoenbach
authors.forename: Shu
authors.initials: S
authors.lastname: Xiao
mesh_terms: D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004533:Egtazic Acid / Q000494:pharmacology; D004560:Electricity; D006801:Humans; D008027:Light; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology; D012542:Scattering, Radiation; D013997:Time Factors
chemical_list: D009942:Organometallic Compounds; C110932:tetramethyl rhodamine ethyl ester; D004533:Egtazic Acid; D002118:Calcium