The effect of 3H-thymidine on the proliferation of in vitro cultured mammalian cells.

The effect of 3H-thymidine on the proliferation of Chinese hamster cells (clone V79) was studied. Following 3H-thymidine application the proliferation of cells (studied on the basis of plating efficiency) was found to be diminished, the drop being dependent on radioactivity (2-20 kBq/ml cultivation medium), the time of application (2-20 h) and specific activity of 3H-thymidine added. Exogenous macromolecular DNA was able to repair, to an important degree the radiotoxic effect of 3H-thymidine on V79 cells by a mechanism other than the mere reduction of specific activity of 3H-thymidine.