A method has been developed for study of the type 2 epithelial cell population in situ in BALB/c mouse lung by measurement of the uptake of [14C]thymidine into DNA of pulmonary cells after stimulation with the antioxidant butylated hydroxytoluene (BHT). Within 2 days of BHT injection there was a marked increase in total lung weight, total labeling index, and [14C]thymidine incorporation. Autoradiographic procedures revealed that the proliferative response 2 days after BHT was due primarily to type 2 alveolar cells, which comprised 80% of the [3H]thymidine-labeled lung cells at that time. Therefore it appeared that this system might provide a means of monitoring the type 2 cell population after irradiation. Radiation modified the BHT-induced proliferative response in a dose-dependent manner, but it did not alter the relative number of labeled cell types in the lung. Thus 2 days after mice were treated with irradiation and BHT, when the proliferative response was due to type 2 cells, [14C]-thymidine incorporation and DNA levels in the lung were determined after various doses of 300-kVp X rays and fission neutrons. Dose-response curves were generated from these data, and the radiation response was characterized by the reciprocal of the slope of the exponential region of the curves, designated D0(PF). When irradiation was followed immediately by the proliferative stimulus BHT, the D0(PF) values were 120 rad for 300-kVp X rays and 60 rad for fission neutrons. Based on these D0(PF) values, relative biological effectiveness of 2.0 was obtained.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging