Effects of Low-Level α Radiation on Intracellular Energy Metabolism

The effect on the adenosine triphosphate (ATP) content of cell samples irradiated with α particles of a mean LET of 135-141 keV/μm is described. Cells in logarithmic growth phase showed an ATP content about 50% below the unirradiated control value 5-15 sec after receiving a mean cellular dose of 25 rad (0.25 Gy). This was followed by a slow recovery up to control values after about 30 sec. Stationary cells responded with an increase in ATP content about threefold over that of the controls 20 sec after irradiation. Within the following 20 sec these elevated ATP values decreased to control levels. Additional measurements of 14 C uptake also showed pronounced differentiated changes in carbon uptake after irradiation for cells in logarithmic and stationary growth phase. The possible importance of these effects on bioenergetic processes as a compensatory reaction of the cellular system to an increased demand for energy is discussed.