Abstract
The radiation protection of cysteamine for high-LET [linear energy transfer] radiations was measured with synchronized Chinese hamster V79 [lung fibroblast] cells. A high concentration (75 mM) of cysteamine provided protection against X rays and 90 and 170 keV/.mu.m He ions. The extent of protection decreased with increased LET value but was substantial with the highest-LET radiation. The approximate dose-modifying factor for G1/S cells was decreased from 4.8 to 1.6 and for late-S cells from 3.2 to 1.5. The shape of the high-LET survival curves for both cell cycle times was preserved as expected for a dose-modifying agent.