Energy metabolism and ATP turnover time during the cell cycle in roentgen irradiated Ehrlich ascites tumour cells.

The cell-cycle related energy metabolism after roentgen irradiation of in vivo growing Ehrlich ascites tumour cells was investigated in cell fractions obtained by elutriator centrifuging. The oxygen consumption and the lactate and pyruvate production, measured in vitro after 4.5, 5 and 9 Gy up to 24 h, were undisturbed, while the decrease in the in vivo ATP content was dose-independent in all parts of the cell cycle. On the basis of these data the ATP turnover time was found to be decreased. The decrease in the ATP content is considered to be less likely to be due to membrane leakage or increased ATP consumption than to reduced ATP production. Since in vitro incubation normalizes the ATP content, it is suggested that environmental factors in the ascites liquid after irradiation cause a decrease in the ATP production. Low ATP contents of the cells do not appear to influence the irradiation-induced changes in the cell flow through the cell cycle.