Transmembrane potentials induced

Marszalek, P. Liu, T. S. Tsong, T. Y. Schwan equation and transmembrane potential induced by alternating electric field. Biophys. J. 58, 1053-1058. 

Inayat-Hussain SH, Annuar BO, Din LB, Ali AM, Ross D. Loss of mitochondrial transmembrane potential and caspase-9 activation during apoptosis induced by the novel styryl-lactone goniothalamin in HL-60 leukemia cells. Toxicol In Vitro 2003 17 433-439. 

The involvement of mitochondria in the pro-apoptotic effects of carotenoids has been clearly demonstrated by the fact that P-carotene induces the release of cytochrome c from mitochondria and alters the mitochondrial membrane potential (Aym) in different tumor cells (Palozza et al., 2003a). Moreover, the highly polar xanthophyll neoxanthin has been reported to induce apoptosis in colon cancer cells by a mechanism that involves its accumulation into the mitochondria and a consequent loss of mitochondrial transmembrane potential and releas of cytochrome c and apoptosis-inducing factor (Terasaki et al., 2007). 

Roberg, K., 2001, Relocalization ofcathepsin D and cytochrome c early in apoptosis revealed by immunoelectron microscopy. Lab. Invest. 81 149-158 Roberg, K., Johansson, U., and OUinger, K., 1999, Lysosomal release of cathepsin D precedes relocation of cytochrome c and loss of mitochondrial transmembrane potential during apoptosis induced by oxidative stress. Free Radio. Biol. Med. 27 1228-1237 Roberg, K. and OUinger, K., 1998, Oxidative stress causes relocation of the lysosomal... 

F. P. Wachs, R. C. Krieg, C. M. Rodrigues, H. Messmann, F. Kullmann, R. Knuchel-Clarke, J. Scholmerich, G. Rogler and K. Schlottmann, Bile salt-induced apoptosis in human colon cancer cell lines involves the mitochondrial transmembrane potential but not the CD95 (Fas/Apo-1) receptor, Int. J. Colorectal Dis., 2005, 20(2), 103. 

BLM, the type and concentrations) of the electrolytes bathing the BLM, the ions adsorbed on the BLM surface, and the extent to and frequency with which the BLM is bent [419]. These experimental observations have led to a phenomenological definition of the flexoelectric coefficient, f, as the ratio between the bending-induced transmembrane potential, Uf, and the change of curvature, c, that accompanies the bending of the membrane ... 

Stimulation of active H+ extrusion from roots (Cesco, 1995 Pinton et al., 1997 Table 9.1) and transmembrane potential hyperpolarization (Slesak and Jurek, 1988) indicated the involvement of the PM H+-ATPase in the increased nutrient uptake generally observed in the presence of humic substances. Direct proof of an interaction between humic molecules and the PM H+-ATPase has been obtained by Vara-nini et al. (1993), who demonstrated that low-molecular-weight (<5kDa) humic molecules at concentrations compatible with those present in the rhizosphere can stimulate the phospho-hydrolytic activity of this enzyme in isolated PM vesicles (Table 9.1). Further proof of the action of humic molecules on PM FT-ATPase activity and on nutrient uptake mechanisms was obtained when studying the effect of these molecules on NO3 uptake. Transport of this nutrient is a substrate-inducible process and involves FT co-transport. At higher uptake rates, the levels and activity of root PM FT-ATPase increased (Santi et al., 1995). The short-term (4h) contact... 

At low frequencies, the external field induces an alternating voltage which is superposed on the resting (dc) transmembrane potential. As frequencies rise and the membrane capacitance dominates its electrical behaviour, this induced voltage drops to a very low level. 

Fig. 16. Top The illustration shows the variation of the induced transmembrane potential of a cell with frequency and with the conductivity of the external medium. The induced potential increases with external conductivity. However, it also decreases with frequency and above about 5 or 10 MHz the induced potential has fallen below 10 mV in most practical cases. Cells can be cultivated for days in fields of high MHz frequencies.

If f<total potential difference applied across the cell is developed across the membrane capacitance. In this limit, the induced membrane potential AV across a spherical cell is AV = 1.5 ER, where E represents the applied external field. Thus the cell samples the external field strength over its dimensions and delivers this integrated voltage to the membranes, which is a few mV at these low frequencies for cells larger than 10 ym and external fields of about 1 V/cm. These transmembrane potentials can be biologically significant. 

Lizard, G., Miguet, C., Bessede, G., Monier, S., Gueldry, S., Neel, D., Gambert, P. 2000. Impairment with various antioxidants of the loss of mitochondrial transmembrane potential and of the cytosolic release of cytochrome c occurring during 7-ketocholesterol-induced apoptosis. Free Radic. Biol. Med. 28, 743-753. 

Photosynthesis is the natural complement to respiration. Photons from the sun induce charge separation in a membrane-bound redox chain, ultimately producing a transmembrane potential for ATP synthesis. In green plants, algae, and... 

While vesicle deformation in AC fields concerns stationary shapes, DC pulses induce short-lived shape deformations. In different studies, the pulse duration has been typically varied from several microseconds to milliseconds, while studies on cells have investigated a much wider range of pulse durations-from tens of nanoseconds to milliseconds and even seconds [80], as discussed in other chapters of this book. Various pulse profiles, unipolar or bipolar, as well as trains of pulses have been also employed (e.g., [81, 82]). Because the application of both AC flelds and DC pulses creates a transmembrane potential, vesicle deformations of similar nature are to be expected in both cases. However, the working fleld strength for DC pulses is usually higher by several orders of magnitude. Thus, the degree of deformation can be different. 

The effective electrical tension, transmembrane potential, Pja, is defined by the Maxwell stress tensor [59, 89, 92]... 

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