Biological and Experimental Electric Fields

In living organisms electric fields of sufficiently high intensity and of variations large enough to affect chemical processes are encountered not only within membrane phases, but also near the surfaces of membranes and protein organizations, for instance at the active sites of enzymes and receptors.  

The observed membrane potential differences, of up to 100 mV may correspond to average values of the electric field strength, of about 100kVcm when the thickness, rf, of the dielectric membrane part is about 10 nm. 

The field intensities which are experimentally accessible are limited by dielectric breakdown. In aqueous solutions, fields up to 150 kV cm may be controlled over distances in the millimeter and centimeter range. It is an additional limitation that in ionic solutions electric fields cannot be maintained for a long time. Owing to ionic currents the field will decrease and Joule heating may cause appreciable temperature increases. These problems can be minimized by applying field pulses of limited duration to ionic solutions and suspensions. In any case, the maximum homogeneous fields that can be experimentally achieved are comparable to the maximum values of electric fields encountered in biomembranes. 

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