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), Journal Name: Radiat. Res.; (United States) Vol. 91:1; ISSN RAREA
- Country of Publication:
- United States
- Language:
- English
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANALEPTICS
BIOLOGICAL EFFECTS
BIOLOGICAL PATHWAYS
BIOLOGICAL RADIATION EFFECTS
CAFFEINE
CELL CYCLE
CELL KILLING
CENTRAL NERVOUS SYSTEM AGENTS
CULTURE MEDIA
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTROMAGNETIC RADIATION
HELA CELLS
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PURINES
RADIATION EFFECTS
RADIATIONS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
X RADIATION
XANTHINES