title: Modification of effects of radiation on thymidine kinase.
abstract: Thymidine kinase (TdR-K) and the incorporation of iododeoxyuridine (IUdR) into DNA of murine bone marrow cells are acutely and temporarily inhibited by low doses (0.01 Gy) of whole-body gamma-radiation with a maximal effect at 4 h after exposure and full recovery at 10 h. The inhibitory effect was totally abolished by whole-body exposure to a strong static magnetic field of 1.4T. The present investigation was designed to gain insight into the mechanism(s) underlying the inhibition of TdR-K activity and the incorporation of 125I-UdR by challenging the system with various pharmacological and biochemical means. To this end the response of TdR-K and 125I-UdR incorporation into DNA to the administration of actinomycin-D, cycloheximide, cysteamine, misonidazole and procaine hydrochloride as well as to dietary manipulations, i.e. vitamin E deficiency and enrichment of the diet by soya oil, and to changes in the glutathione levels were investigated in bone marrow cells of irradiated and sham-irradiated mice. Furthermore, the effect of various NaHCO3 concentrations on optimizing the radiation-induced inhibition of TdR-K was investigated under conditions of radiation, vitamin E deficiency and enrichment of the diet by soya oil. The data point to the involvement of the cellular radical-detoxification system in changing the activity of TdR-K, especially on the basis of the concurrent increase of glutathione concentration and decrease in TdR-K activity.
authors.affiliation: Institute for Medicine, Nuclear Research Center Jülich GmbH, FRG.
authors.forename: K
authors.initials: K
authors.lastname: Hohn-Elkarim
authors.forename: H
authors.initials: H
authors.lastname: Mühlensiepen
authors.forename: K I
authors.initials: KI
authors.lastname: Altman
authors.forename: L E
authors.initials: LE
authors.lastname: Feinendegen
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D002588:Cesium Radioisotopes; D004247:DNA / Q000378:metabolism; D005260:Female; D005720:Gamma Rays; D007065:Idoxuridine / Q000493:pharmacokinetics; D008280:Magnetics; D051379:Mice; D013937:Thymidine Kinase / Q000378:metabolism / Q000528:radiation effects*; D014916:Whole-Body Irradiation
chemical_list: D002588:Cesium Radioisotopes; D004247:DNA; D013937:Thymidine Kinase; D007065:Idoxuridine