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 significant increases above non-irradiated rats in 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 indicate a reduced 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 increase of irradiation doses (50 to 600 rads) causes a 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.