M. MOUSTAFA *, A.M. EL-KHATIB**, N.K. MADI**, SAMIA REZK***, A.M. ELHAJ**
*Department of Medical Biophysics, Medical Research Institute (MRI), Alexandria University Egypt
**Department of Physics, Faculty of Science, Alexandria University, Egypt
*** Department of Radiology, Faculty of Medicine, Alexandria University, Egypt
Abstract. In vivo measurements for whole body exposed to doses 50 – 600 rads and ex vivo measurements of dielectric properties of excised tissues are carried out at 10 days post-irradiation using multiple frequency bioelectrical impedance analysis (MFBIA). Changes in the extracellular water (ECW) and total body water (TBW) of rats are estimated. The results show a significant increases above non-irradiated rats in an intracellular water (ICW) by 11.61% (P = 0.0001) and ECW by 9.95% (P = 0.0216) of rats exposed to 600 rads. These significant changes indicating a reduced in the activity of the ion pumps, which leads to changes in ion distribution between inter- and extra-cellular spaces. Dielectric properties (permittivity and conductivity) of freshly excised samples are measured at frequencies between 100 Hz and 5 MHz using two-electrode technique. The results for liver and muscle tissues reveal differences between non-irradiated and irradiated tissues (600 rads). The irradiation of rats with 600 rads causes 17% (P = 0.1139) non-significant decrease in the conductivity and 26% (P = 0.0091) significant decrease in the permittivity of liver below that of non-irradiated. While irradiation of rats causes significant increases by 19% (P = 0.005) and 25% (P = 0.0217)) in conductivity and permittivity of rat muscle tissues, respectively. Also the increasing of irradiation doses (50 to 600 rads) causes decrease on the characteristic frequency (the point of the maximum value for the reactive component of impedance.). This indicates that there is a variability of the electrical properties which could be used as indicator to determine the degree of damage of tissue due to irradiation.
Key words: Extracellular water, conductivity, permittivity, muscle tissues.
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