Incorporation of C14-thymidine and C14-uridine nucleosides into nucleic acid molecules in the liver of mice exposed to trivalent arsenic in drinking water.
The effect of trivalent arsenic on the C14-thymidine and C14-uridine incorporation into the liver nucleic acid molecules was studied in groups of mice exposed to 3.3 mmol . l-1 sodium arsenite in drinking water for 2, 4, 8, 16 and 32 days. In each exposure group, 18 h before the animals were killed by decapitation, six to ten mice were injected with 0.1 ml of C14-thymidine or C14-uridine of an activity of 0.37 MBq. The radioactivity of liver DNA and liver RNA fractions isolated and separated by extraction from the mouse liver homogenate was measured on a Betazcint BZ 5,000 scintillation counter and expressed as cpm . mg-1 of isolated nucleic acids. Initially, the rates at which the labeled thymidine and uridine nucleosides incorporated into the nucleic acid molecules showed a marked drop below the control value, then started to rise again, continuing to gradually increase as the time of arsenic exposure was increasing; they attained the control value on day 8, and at the last interval of observation (i.e. at 32 days of exposure to arsenic) they reached, respectively, 143% and 127% of the control value. The initial drop in the rate of nucleoside incorporation is believed to reflect the general metabolic inhibition caused by arsenic; the subsequent enhancement of the process of incorporation is ascribed to the induction of enzymes that are involved in the development of a tolerance for arsenic.
Benes
B
B
Bencko
V
V
D000818:Animals; D001151:Arsenic / Q000494:pharmacology*; D018053:Arsenites; D002250:Carbon Radioisotopes; D004247:DNA / Q000096:biosynthesis*; D005260:Female; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D012313:RNA / Q000096:biosynthesis*; D017670:Sodium Compounds; D013936:Thymidine / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism*
D018053:Arsenites; D002250:Carbon Radioisotopes; D017670:Sodium Compounds; C017947:sodium arsenite; D012313:RNA; D004247:DNA; D001151:Arsenic; D013936:Thymidine; D014529:Uridine