Eagle's MEM Research Articles

Mortality patterns of mouse Sarcoma 180 cells resulting from direct heating and chronic microwave irradiation

Summary Mortality patterns were essentially identical for irradiated and non-irradiated cells, suspended in Eagle's MEM, when radiation induced heat was dissipated at a rate which insured comparable temperatures for both experimental and control systems. Cell suspensions were irradiated with a field intensity of approximately 0.3 watts/cm 2 at control temperatures ranging from 43° to 48°C. Survival data were fitted to a hypothetical curve of the inverse, sigmoid type. The equation of this curve is commonly referred to as Gompertz's equation and may be expressed as − dX/dt = aX exp ( bt ), where − dX/dt indicates the rate of decay of surviving cells ( X ), and a and b are decay coefficients. The coefficient a at zero time approximates a first order rate coefficient. The coefficient b represents a type of “decay acceleration” coefficient which may be associated with a decreasing quantity of hypothetical “protective or vital material” present in the system. When plotted as a function of the reciprocal of the absolute temperature, values of log a assumed a linear regression as would be predicted by the Arrhenius equation. Activation energies obtained for the Arrhenius plots, 72.4±9.8 and 70.8±7.7 kcal/mole for control and experimental systems respectively, were not significantly different. The high temperature dependence suggests a “spontaneous” destruction of cellular material. Although significantly different from zero, values of b coefficients were not sufficiently precise to permit a meaningful interpretation of their temperature trend. Cell decay appeared to be highly temperature dependent as would be expected from the “spontaneous” destruction of cellular material. It was also shown in this investigation that in microwave studies concerned with some form of cellular destruction, undetected temperature deviations between irradiated and control systems of no greater than one degree could lead to erroneous interpretations. In investigations concerning the effects of high frequency electromagnetic irradiation on the biological system, especially when some form of cellular destruction is involved, temperature control is a major consideration.