Productive Death of Mammalian Cells Due to ETA-radiation from Incorporated Thymidine Labelled With 3H or 14C

Abstract

Survival of mammalian cells cultured in vitro has been determined following incorporation of thymidine labelled with ³H or ¹⁴C. Survival decreased with increase of concentration in the medium (μc/ml) and also with thymidine specific activity (mc/μmole), the latter effect being much greater at higher concentration levels. After 48 hr incubation at a concentration of 0.05 μc/ml at a specific activity of 2 mc/μmole, there were no surviving cells capable of forming colonies. Approximately the same survival was obtained with ³H- and ¹⁴C-thymidine for the same concentration of 0.5 μc/ml at a specific activity of 0.03 mc/μmole and estimates show that, because of the different particle ranges for the two isotopes, the nuclear radiation dose would be similar under these conditions. The possible hazard of ³H thymidine at very high specific activity is emphasized.