Radiosensitivity of pulmonary alveolar macrophages in rats exposed to local X-irradiation

The radiosensitivity of pulmonary alveolar macrophages (PAMs) in rats exposed to local thoracic X-irradiatoin was studied. The percentages of mitotic and labeling cells were used as biological endpoints. The parameters of radiosensitivity of PAMs obtained on the second day after local exposure are as follows: D0 = 0.68 Gy, Dq = 0.06 Gy, n = 1.1 for mitotic cells and D0 = 1.04 Gy, Dq = 0.12 Gy, n = 1.12 for labeling cells. The parameters of radiosensitivity of PAMs in bronchical lavage obtained immediately after X-irradiation are: D0 = 3.56 Gy, Dq = 0.77 Gy, n = 1.24 for labeling cells and D0 = 3.69 Gy, Dq = 0.35 Gy, n = 1.1 for mitotic cells. The comparison of thses results indicates that the radiation effect on PAMs obtained immediately after X-irradiation is less severe than that of PAMs obtained 2 days later. It might be caused by the delay of cell cycle within 2 days after X-irradiation