Abstract
The effects of treatment with benzarnide, an inhibitor of adenosine diphosphate (ADP) ribosyl transferase, were studied in two strains of L5178Y lymphoma cells of differential sensitivity to ionizing radiation. Continuous 2 rnmoYl benzamide treatment enhanced the killing effect of roentgen irradiation in the sensitive cells, but not in the resistent cells. Three hours' treatment with 2 to 15 mmoVl benzarnide sensitized irradiated cells of both strains to a similar extent. Rejoining of DNA breaks was delayed by 2 mmoVl benzamide in sensitive cells more than in resistant cells.