pH changes induced by EGT and ECT pulse delivery in tissues

MAGLIETTI FELIPE; MICHINSKI SEBASTIAN; OLAIZ NAHUEL; CASTRO MARCELO; SUAREZ CECILIA; MARSHALL GUILLERMO

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Conferencia; The Complex Membrane in the electric field; 2010

Goron Research Conferences

Introduction In previous work [cita] we showed that ECT pulse delivery induced extreme pH changes in gels. This pH changes were more intense when the same dose of current was administered by pulses rather than continuously (EChT). Now we show the pH changes induced in a tissue by administering ECT and EGT pulses, and how the tissue buffer neutralizes it. Materials and Methods An ex vivo model of muscular chicken tissue was used. A pH indicating die (phenolphthalein) was put in the surface of the tissue, and over it the electrodes were placed. Right after pulse delivery the die changed from colorless to red, indicating the pH change, which lasted from seconds to minutes. As the tissue buffer neutralizes the pH change, the die again changed from red to colorless, indicating that the tissue buffer was around 7 again. High resolution videos were taken. We called the time needed for neutralizing 90% of the die, evanesce time. Image Analysis The videos obtained from the experiments were crop to extract the area surrounding the electrodes. Using fuzzy-c-means method the image was segmented, and the number of pixels corresponding to the die in each frame, were counted using an automated Matlab script. The number of pixels counted was increasingly less as the die turned colorless. The evanesce time, when the number of pixels corresponding to the die was reduced by 90%, was automatically obtained using the same script. Results ECT pulse delivery induce pH changes in tissue that were neutralized by the buffer present in the tissue in less than 5 seconds. EGT pulse delivery induced pH changes in tissue that lasted long enough to irreversible denaturate DNA plasmids. By reducing any of the pulse parameters to its half, the time needed by the tissue buffer to neutralize the pH change induced, was dramatically reduced. In the other hand, raising any of the parameters significantly increased the evanescence time, and thus extended the exposure time of the plasmids to extreme pH conditions.