Effect of post-irradiation temperature on viability of rat thymocytes

SummaryRat thymocyte suspensions were exposed to X-rays (50 to 1000 R). After incubation with 10 mM glucose at 37°C, pH 7·4 for 2 to 8 hours, cell viability, ATP, fructose-1,6-diphosphate and dihydroxyacetone phosphate were measured. The results confirmed the close relationship between viability (judged by a dye-exclusion test) and ATP content, and the correlation between decreasing ATP and the accumulation of these two glycolytic intermediates. Lowering the incubation temperature from 37°C to 25°C, or pH from 7·4 to 6·1 prevented the appearance of dead cells, ATP depletion, and the accumulation of the intermediates. On the basis of this experimental evidence, a new hypothesis for the mechanism of interphase death, namely, the stimulation of ATP degradation through an abnormal enhancement of the phosphofructokinase reaction, is proposed. It explains satisfactorily many experimental results, including the marked post-irradiation temperature effect.