COMPARATIVE CLASTOGENIC SENSITIVITY OF RESPIRATORY-TRACT CELLS TO GAMMA-RAYS

To understand the relationships between exposure and damage to differe nt cell populations in the respiratory tract, methods were developed t o culture deep-lung fibroblasts and epithelial cells from the nose, tr achea and deep lungs. Female F-344 Fischer and male Wistar rats were e xposed to 1-5 Gy of Co-60 gamma rays at a dose rate of 0.4 Gy/min. Cel ls were isolated for short-term culture, and the incidences of binucle ated cells and micronuclei were determined. The incidences of micronuc lei were determined in cytochalasin-B-induced binucleated cells at 72 h for nasal and tracheal tissue and 96 h for deep-lung fibroblasts and epithelial cells. Maximum frequencies of binucleated cells were found in the control nonirradiated cells at these harvest times, and the fr equencies were not significantly affected at these harvest times by ra diation exposure. No significant differences were found in the frequen cies of micronuclei induced in the nasal epithelial cells isolated fro m female F-344 Fischer or male Wistar rats. Fibroblasts cultured in di fferent media and isolated from either female F-344 Fischer or male Wi star rats also showed a similar frequency of micronuclei. Over the dos es tested, the frequency of micronuclei in the respiratory tract cells increased linearly with the dose. The slopes were 92.2 +/- 9.2, 76.2 +/- 7.9, 32.8 +/- 2.4 and 28.7 +/- 3.4 micronuclei/1000 binucleated ce lls/Gy for deep-lung epithelial cells, deep-lung fibroblasts, tracheal epithelial cells and nasal epithelial cells, respectively. Deep-lung epithelial or fibroblast cells were about two to three times as sensit ive for clastogenic damage as nasal and tracheal epithelial cells. The measurement of micronuclei in isolated respiratory tract cells is ver y useful in assessing cytogenetic damage induced in different cell typ es by radiation. (C) 1997 by Radiation Research Society.