Intracellular radiation of HeLa cells by tritiated thymidine

SummaryThe production of lactic acid by irradiated and unirradiated HeLa cells, grown as monolayer, was investigated. As long as exponential growth was maintained, the lactic acid production was proportional to the increase in cell number, and the production per hour and per cell was constant. When tritiated thymidine was added to the medium, a significant increase of 23 per cent of the lactic acid production per hour and per cell was found for the highest doses. The findings are discussed with regard to the proposed equations and related to the calculation methods of other workers.