Differences in Cell-Cycle Progression Delays after Exposure to 238 Pu a Particles Compared to X Rays

Abstract

Cultured Chinese hamster lung cells (V79) were exposed to 238Pu .alpha. particles of 250 k Vp X-rays at doses resulting in similar cell survivals (i.e., 50, 10 and 1%). The DNA distributions of cells at different times after radiation exposure were measured using flow cytometry. After exposure to .alpha. particles V79 cells evidently showed significantly prolonged late S phase delay compared to X-rays for comparable cell-killing doses. Retention of cells in late S subsequent to .alpha.-particle exposure caused a longer mitotic delay compared to X-rays for a given survival level. For the endpoint of mitotic delay the RBE [relative biological effectiveness] for high-LET [linear energy transfer] radiation apparently is higher than the RBE for cell killing.