THE ACTION OF X RAYS AND CYTOSTATIC COMPOUNDS ON DPN CONTENT AND DNA SYNTHESIS IN ASCITES TUMOR CELLS (in German)
Changes in DPN (diphosphopyridine nucleotide) content and incorporation of thymidine-H/sup 3/ by DNA were studied in tumor cells irradiated in vitro with 3000 r. DPN content decreased 63% and DNA synthesis 58% 20 min after irradiation in the absence of nicotinamide. When nicotinamide was added to the cultures in a final concentration of 4 x 10/sup -3/M, the respective decreases were only 10 and 16%. Thus irradiated tumor cells exhibit parallel changes in DPN contents and DNA synthesis, and both these processes can be restored in part by nicotinamide. The extent of the irradiation damage in regard to both these parameters is greatly influenced by the conditions during the incubation. Ethylenimines, H/sub 2/O/sub 2/, and organic peroxides cause similar changes and appear to be true radiomimetics in the system studied. The primary damage to DPN content and DNA synthesis is a potentially reversible process. Only under higher irradiation doses or higher concentrations of cytostatics is secondary and irreparable injury superimposed. The main feature of the latter is inhibition of DPN synthesis. These results show the dependence of DNA synthesis on the DPN content of the cells. They also provide evidence for dependence of the initial and rapid decrease in DPN on a release of nicotinamide by the cells into the incubation medium. The possibility of activation of DPNase being involved in this loss is discussed. (H.H.D.)
- Research Organization:
- Universitat, Hamburg
- NSA Number:
- NSA-17-033639
- OSTI ID:
- 4672419
- Journal Information:
- Biochemische Zeitschrift (West Germany) Superseded by Eur. J. Biochem., Journal Name: Biochemische Zeitschrift (West Germany) Superseded by Eur. J. Biochem. Vol. Vol: 336; ISSN BIZEA
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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