Radiation-induced decrease in influx rates of potassium ions into thymocytes in vitro in relation to decreased intracellular adenosine triphosphate concentrations.

The relationship between decreases in the adenosine triphosphate content of irradiated thymocytes and observed changes in the influx constant values for potassium ions in the same cells have been investigated. The results suggest that radiation-reduced ATP concentrations may be a rate-limiting factor controlling the active transport of potassium, 3--4 hours after X-irradiation in the range 2--20 krad. However, over the first hour of incubation, post-exposure ATP levels have not decreased sufficiently to be a major factor in the observed decrease in active uptake of potassium ions. This evidence is supported by comparisons of the influence of 1 mM adenine on radiation-reduced ATP levels and influx constants over the first hour after irradiation.