Relationship between double strand break rejoining and G2 block formation in V79 cells

Caffeine and hypertonicity affect the survival of gamma-irradiated Chinese Hamster V79 cells in different ways: while caffeine reduces the shoulder of the dose effect curve, hypertonic treatment mainly affects its final slope suggesting that different types of damage and (or) repair mechanisms are i...

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Bibliographic Details
Published in:Radiation and environmental biophysics 1986-01, Vol.25 (1), p.13-21
Main Authors: Weibezahn, K F, Coquerelle, T M
Format: Article
Language:English
Subjects:
Animals
Caffeine - pharmacology
Cell Line
Cell Survival - drug effects
Cell Survival - radiation effects
Cricetinae
Cricetulus
DNA - radiation effects
Gamma Rays
Interphase - drug effects
Interphase - radiation effects
Kinetics
Lung
Osmolar Concentration
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Summary:Caffeine and hypertonicity affect the survival of gamma-irradiated Chinese Hamster V79 cells in different ways: while caffeine reduces the shoulder of the dose effect curve, hypertonic treatment mainly affects its final slope suggesting that different types of damage and (or) repair mechanisms are involved. Rejoining of DNA double strand breaks (dsb), as measured by neutral filter elution technique, exhibits a fast and a slow component, indicating that dsb rejoining consists of two different processes. Hypertonicity causes a temporary inhibition of the fast rejoining step but has no effect on the overall rejoining efficiency. Thus, it appears that its sensitizing effect on survival is not correlated with impaired dsb rejoining. Caffeine was found to inhibit the rejoining of dsb even after 6 h but the length of G2 phase was normal. By contrast, hypertonically treated cells are blocked in G2 but rejoining of dsb was normal. From these results we conclude that successful rejoining of part of the dsb involves arresting the cells reversibly in G2.
ISSN:0301-634X
1432-2099
DOI:10.1007/BF01209680