Abstract
In studies on embryonic induction, unexpected results were obtained when cultured kidney tissue from mouse embryos was pulse-labeled with 3H-thymidine or-adenine and then subcultivated. A 2-h pulse of 20 μCI led in 2-3 days to morphologically detectable cell death in the mesenchyme and to impaired growth. After day 1, the DNA content of untreated control explants increased linearly, whereas no increase occurred in labeled explants until day 4, when a linear growth phase ensued. On day 8 the DNA content was 50-60% of the controls. Onset of linear growth coincided with the disappearance of label from the acid-insoluble fraction of the tissues, suggesting elimination of the initially labeled cells. In tissues treated with high pulses, the adenylate energy charge in the acid-soluble extracts decreased to 0.5.
We postulated that radiation-induced DNA damage activates poly(ADP-ribose)polymerase, which leads to consumption of NAD and a rapid drop in the ATP-level, eventually resulting in cell death. Dose-dependence experiments supported our hypothesis: labeling of the acid-insoluble fraction increased linearly until a pulse of 10 μCi 3-H-adenine, whereafter the curve leveled off. The critical point corresponds to ca. 1-5 DPM/ng DNA. The leveling-off was prevented by 3-aminobenzamIne, an inhibitor of poly(ADP-ribose) polymerase.
Our findings suggest that subseguent cell growth may be affected by rather low doses of low-energy radiation.
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Salonen, J., Raivio, K. & Saxén, L. 124 ARTEFACTS DUE TO RADIATION-INDUCED CELL DAMAGE IN PULSE-LABELING EXPERIMENTS USING TRITIATED NUCLEIC ACID PRECURSORS. Pediatr Res 24, 131 (1988). https://doi.org/10.1203/00006450-198807000-00148
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DOI: https://doi.org/10.1203/00006450-198807000-00148