Theoretical evaluation of voltage inducement on internal membranes of biological cells exposed to electric fields

¹ University of Ljubljana

^* To whom correspondence should be addressed. E-mail: tadej{at}lbk.fe.uni-lj.si.

Submitted on July 14, 2005
Revised on August 24, 2005
Accepted on 4 October 2005

	Abstract

Several reports have recently been published on effects of very short and intense electric pulses on cellular organelles; in a number of cases, the cell plasma membrane appeared to be affected less than certain organelle membranes, while with longer and less intense pulses the opposite is the case. The effects of electric pulses are the consequence of the voltages they induce on the membranes, and in this paper we investigate the conditions under which the induced voltage on an organelle membrane could temporarily exceed its counterpart on the cell membrane. This would provide a possible explanation of the observed effects of very short pulses. Frequency-domain analysis yields an insight into the dependence of the voltage inducement on the electric and geometric parameters characterizing the cell and its vicinity. We show that at sufficiently high field frequencies, there is a range of parameter values for which the voltage induced on the organelle membrane can indeed exceed the voltage induced on the cell membrane. Particularly, this can occur if the organelle interior is electrically more conductive than the cytosol, or if the organelle membrane has a lower dielectric permittivity than the cell membrane, and we discuss the plausibility of these conditions. Time-domain analysis is then used to determine the courses of the voltage induced on the membranes by pulses with risetimes and durations in the nanosecond range. The particularly high resting voltage in mitochondria, to which the induced voltage superimposes, could contribute to the explanation why these organelles are the primary target of many observed effects.

Key Words: cell plasma membrane, induced membrane voltage, membrane conductivity, membrane permittivity, organelle membranes

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