title: Radiotoxicities of [3H]thymidine and of [3H]arginine compared in mouse embryos in vitro.
abstract: Tritium that is bound to organic molecules is of special risk for living systems, in particular when such molecules are components of the cell nucleus. Therefore, [3H]thymidine and [3H]arginine were studied for radiotoxicity in early mammalian embryo development. Starting with the two-cell stage, mouse embryos were incubated in vitro with [3H]thymidine or [3H]arginine at either 370 Bq/ml (10 nCi/ml) or 925 Bq/ml (25 nCi/ml). Development in vitro was followed up to the formation of the inner cell mass at 192 h postconception (p.c.). There was no difference in radiotoxicity of the two substances with respect to cell proliferation; however, formation of blastocysts, hatching of blastocysts, trophoblast outgrowth, and formation of inner cell mass were impaired more strongly by [3H]arginine than by [3H]thymidine when the external exposure concentrations were the same. Similarly, micronuclei were seen in blastocysts at 96 h p.c. at higher frequency after incubation with [3H]arginine. However, uptake of [3H]arginine by the embryos was considerably faster than that of [3H]thymidine, and this most probably accounts for the apparent difference in radiotoxicity.
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism; D001693:Biological Transport, Active; D002455:Cell Division / Q000528:radiation effects; D002467:Cell Nucleus / Q000528:radiation effects / Q000648:ultrastructure; D005314:Embryonic and Fetal Development / Q000528:radiation effects*; D005260:Female; D008297:Male; D051379:Mice; D009924:Organ Culture Techniques; D011247:Pregnancy; D013936:Thymidine / Q000008:administration & dosage / Q000378:metabolism; D014316:Tritium / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D014316:Tritium; D001120:Arginine; D013936:Thymidine