Action of caffeine on x-irradiated HeLa cells. V. Identity of the sector of cells that expresses potentially lethal damage in G/sub 1/ and G/sub 2/
When HeLa S3 cells are irradiated in early G/sub 1/ with 4 Gy of 220-kV x rays and are then incubated in growth medium containing up to 5 mM caffeine, survival is reduced (as reported previously), reaching a concentration-dependent plateau. Cell killing presumably occurs as a result of the fixation of a portion of the potentially lethal damage the cells contain. These cells respond to continued treatment with caffeine at concentrations greater than 2 mM during S, but less so than during G/sub 1/. When they reach G/sub 2/ arrest, however, extensive cell killing again occurs (reported previously), presumably also the result of potentially lethal damage fixation. G/sub 1/-irradiated cultures that are treated with caffeine either continuously at a concentration in the range 1 to 5 mM, or at 10 mM for 8 hr and subsequently with the low concentration, achieve the same survival level in G/sub 2/, provided that the potentially lethal damage is not repaired during G/sub 1/ and S. Repair seems to be completely inhibited in the presence of 3 to 4 mM caffeine. The results indicate that fixation of potentially lethal damage occurs in the same sector of cells in G/sub 1/ and G/sub 2/, suggesting that the same cellular lesion gives rise to cell killing in the two phases.
- Research Organization:
- Washington Univ., St. Louis, MO
- OSTI ID:
- 6709008
- Journal Information:
- Radiat. Res.; (United States), Vol. 91:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
CAFFEINE
RADIOSENSITIVITY EFFECTS
HELA CELLS
RADIOSENSITIVITY
BIOLOGICAL PATHWAYS
BIOLOGICAL RADIATION EFFECTS
CELL CYCLE
CELL KILLING
CULTURE MEDIA
DOSE-RESPONSE RELATIONSHIPS
X RADIATION
ANALEPTICS
BIOLOGICAL EFFECTS
CENTRAL NERVOUS SYSTEM AGENTS
DRUGS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PURINES
RADIATION EFFECTS
RADIATIONS
XANTHINES
560121* - Radiation Effects on Cells- External Source- (-1987)
520301 - Environment
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