Abstract
To clarify the potential role of high LET radiation-induced carcinogenesis in respiratory tract, the cytotoxicity and transforming ability of gamma-rays and alpha-particles were analyzed utilizing primary cultures of rat lung (RLE) and tracheal epithelial (RTE) cells. The radiation sensitivity and relative biological effectiveness (RBE) for alpha-particles in RLE and RTE cells were compared. The irradiation caused similarly an exponential decrease in survival in RLE and RTE cells, and the D37 of alpha-particles and gamma-rays were 0.65 Gy and 3.6 Gy, respectively. The RBE for cell killing was 5.5 in the both types of cell. The transformation frequencies (TF) for RLE and RTE were 3.7x10-3 and 2.4x10-3 at 2 Gy of alpha-particles, respectively. At 7.5 Gy of gamma-rays, the TF for RLE and RTE increased to 8.0x10-3 and 7.1x10-3, respectively. The RBE for transformation of RLE was 1.7, and that of RTE was 1.3. This primary epithelial cell culture system will be useful for analysis of radiation sensitivity among the different target cells and mechanistic studies of early changes in the rat lung carcinogenesis induced by alpha-particles.
