Results of self-consistent analyses of cells show the possibility of temperature increases at membranes in response to a single nanosecond, high-voltage pulse, at least over small sections of the membrane. Molecular Dynamics simulations indicate that such a temperature increase could facilitate poration, which is one example of a bio-process at the plasma membrane. Our study thus suggests that the use of repetitive high-intensity voltage pulses could open up possibilities for a host of synergistic bio-responses involving both thermal and electrically driven phenomena.
"Our findings suggest that whenever the pulse duration is small compared to the thermal relaxation constant of the cell membrane, and the membrane capacitance drops to its low asymptotic high-frequency value in the pulse spectral bands, one may observe a steep increase in the membrane temperature, up to physiologically significant levels , the average (cytoplasm) temperature remaining essentially unaffected. Similar conclusions were obtained in  following a more sophisticated approach which combines Smoluchowski equation to describe membrane response , the heat equation and molecular dynamics simulations , to gauge the impact of localized membrane heating on membrane poration. "
[Show abstract][Hide abstract] ABSTRACT: A bio tissue model consisting of multilayer spherical cells including four
nested radial domains (nucleus, nuclear membrane, cytoplasm and plasma
membrane) is worked out to derive the cell heating dynamics in presence of
membrane capacitance dispersion under pulsed electromagnetic exposure. Two
possible cases of frequency-dependent membrana models are discussed: plasma and
nuclear membranes are dispersive, only the nuclear memebrane is dispersive . In
both models an high localized heating of the membranes occurs, without
significant temperature rise in the cytoplasm and nucleoplasm.
[Show abstract][Hide abstract] ABSTRACT: Polarization of spectrin-actin undermembrane skeleton of red blood cell (RBC) plasma membranes was studied by impedance spectroscopy. Relatedly, dielectric spectra of suspensions that contained RBCs of humans, mammals (bovine, horse, dog, cat) and birds (turkey, pigeon, duck), and human RBC ghost membranes were continuously obtained during heating from 20 to 70°C. Data for the complex admittance and capacitance were used to derive the suspension resistance, R, and capacitance, C, as well as the energy loss as a function of temperature. As in previous studies, two irreversible temperature-induced transitions in the human RBC plasma membrane were detected at 49.5°C and at 60.7°C (at low heating rate). The transition at 49.5°C was evident from the abrupt changes in R, and C and the fall in the energy loss, due to dipole relaxation. For the erythrocytes of indicated species the changes in R and C displayed remarkable and similar frequency profiles within the 0.05-13MHz domain. These changes were subdued after cross-linking of membranes by diamide (0.3-1.3mM) and glutaraldehyde (0.1-0.4%) and at the presence of glycerol (10%). Based on the above results and previous reports, the dielectric changes at 49.5°C were related to dipole relaxation and segmental mobility of spectrin cytoskeleton. The results open the possibility for selective dielectric thermolysis of cell cytoskeleton.
[Show abstract][Hide abstract] ABSTRACT: Nanosecond (ns) electric pulses of sufficient amplitude can provoke electroporation of intracellular organelles. This paper investigates whether such pulses could provide a method for controlled intracellular release of a content of small internalized artificial lipid vesicles (liposomes). To estimate the pulse parameters needed to selectively electroporate liposomes while keeping the plasma and nuclear membranes intact, we constructed a numerical model of a biological cell containing a nucleus and liposomes of different sizes (with radii from 50 nm to 500 nm), which were placed in various sites in the cytoplasm. Our results show that under physiological conditions selective electroporation is only possible for the largest liposomes and when using very short pulses (few ns). By increasing the liposome interior conductivity and/or decreasing the cytoplasmic conductivity, selective electroporation of even smaller liposomes could be achieved. The location of the liposomes inside the cell does not play a significant role, meaning that liposomes of similar size could all be electroporated simultaneously. Our results indicate the possibility of using ns pulse treatment for liposomal drug release.
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