Comparision of the Effects of X-Radiation on the Elevation of Thymidine Kinase and Thymidylate Synthetase During Liver Regeneration
Investigations were made to determine if exposure to x radiation between 14 and 17.5 hr after surgery might prevent the onset of DNA synthesis in regenerating liver by interfering with the accumulation of thymidylate synthetase. Male albino rats were partially hepatectomized, fasted, and exposed to x radiation. One group was exposed 6 to 7 hr after partial hepatectomy and another group at 15 to 16 hr. The rats were sacrificed and a 60,000 xg liver supernatant fraction was prepared in isotonic KCl. Each supernatant fraction was assayed for thymidine kinase, as well as thymidylate (TMP) synthetase. Kinase activity in the livers of rats irradiated 6 to 7 hr postoperatively was less than 3% of the kinase activity in the livers of unirradiated controls. In the livers of rats exposed to x radiation 15 to 16 hr postoperatively, kinase activity approached 15% of that of unirradiated controls. The activity of TMP synthetase in livers of irradiated rats averaged 75% of that in livers of unirradiated controls, and the effect of early irradiation appeared to be somewhat less than the effect of late irradiation. The failure of early or late x-radiation doses to prevent the elevation of TMP synthetase ruled out the possibility that prevention of the initiation of DNA synthesis by prior irradiation could be attributed to interference with the activity of TMP synthetase. (M.C.G.)
- Research Organization:
- Loma Linda Univ., Calif.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-16-032846
- OSTI ID:
- 4768659
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 9, Issue 1-2; Other Information: Orig. Receipt Date: 31-DEC-62; ISSN 0006-291X
- Publisher:
- Elsevier
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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