A Comparative Study of Several Survival Responses of Mammalian Cells After UV and After X-Irradiation
Dose response curves were obtained from Chinese hamster cells irradiated in different growth stages and under different nutritional conditions with either X-ray or ultraviolet light. All X-ray survival curves were asymptotically exponential, while the shape of the UV-curves was bi-phasic. Survival of X-irradiated cells was much less influenced by cultural factors than survival of cells exposed to UV. Recovery of cells from potentially lethal damage had a T1/2 of 1–2 h after exposure to the ionizing irradiation, while it took considerably longer to recover 50% of the UV induced damage. Similarly “fixation” of X-ray damage was relatively rapid (T1/2 ⋍ 30 min) compared to “fixation” of UV damage (T1/2 ⋍ 3.5 h). Finally, exposure of cells to 43°C for 1 h immediately after X-irradiation resulted in synergistic cell killing and subsequent complete inhibition of recovery from potentially lethal damage. On the other hand similar heat treatment of UV-exposed cells resulted only in additive cell killing and did not inhibit recovery.
KeywordsMethane Filtration Trypsin Pyrimidine Stimul
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- 1.Smith, K.C., Youngs, D.A., and Van der Schueren, E., (1975) in Molecular Mechanisms for Repair of DNA (P.C. Hanawalt and R.B. Setlow, eds.), Part B, pp. 443–451, Plenum Press, N.Y.Google Scholar
- 2.Cleaver, J.E., (1973) Cancer Res. 33, 362–369.Google Scholar
- 7.Ray, G.R., Hahn, G.M., Bagshaw, M.A., and Kurkjian, S., (1973) Cancer Chemother. Rpts. Part I, S7, 473–475.Google Scholar
- 9.Hahn, G.M., (1974) Cancer Res. 34, 3117–3123.Google Scholar
- 10.Li, G.C., Evans, R.G., and Hahn, G.M., (in press) Radiat. Res.Google Scholar
- 11.Regan, J.D., and Setlow, R.B., (1974) Cancer Res. 34, 3718.Google Scholar