Comparative sensitivity of the nuclear and mitochondrial DNA syntheses to X-irradiation and to the administration of a sulfhydryl radioprotector (AET) in normal and regenerating rat liver |
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Authors: | L Baugnet-Mahieu R Goutier C Baes |
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Institution: | (1) Radiobiology Department, Centre d'Etude de l'Energie Nucléaire, Mol, Belgium;(2) University of Liége, Belgium |
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Abstract: | Summary Incorporation of thymidine into nuclear and mitochondrial DNA has been measured in the livers of normal rats and of rats killed 17 h or 24 h after partial hepatectomy. When total-body X-irradiation (500 or 1,500 R) is given at increasing intervals (up to 30 h) before sacrifice, a progressive decrease followed by a plateau of low level of incorporation is observed in the nuclear DNA (N-DNA) whereas the synthesis of mitochondrial DNA (M-DNA) first decreases until a minimal value is reached after 4 h in normal liver and 12 h in regenerating liver, then recovers at an exponential rate, quite independently of the nuclear DNA synthesis.The results suggest that irradiation can interfere with the enzymatic processes of both M-DNA and N-DNA syntheses, but that the persistence of the inhibition of N-DNA synthesis must be ascribed to a temporary block in the cell cycle.The SH-protector AET injected to non-irradiated rats exerts a very small inhibitory effect on normal liver N-DNA and M-DNA synthesis. In regenerating liver, both syntheses are affected rather similarly suggesting a common mechanism of inhibition through impairment of some step in the synthetic process. |
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