Recovery response of dividing cells in the thymus of whole-body gamma-irradiated mice.
Mice were irradiated with different doses of gamma-rays 30 min after the administration of 32P-orthophosphate. The dose-response curves determined at 72 hours after exposure showed an inflection point in the total activity present in the DNA in thymus and spleen. In the low dose-range, the dose-response curves have D0 = 55 rad (n = 2-5) for thymus and DO = 95 rad (n = 2-5) for the spleen. Thirty minutes after the administration of 32P-orthophosphate, the dividing cells from thymus were partially synchronized by the administration of 80 mg per kg body-weight hydroxyurea. At different time-intervals, the mice were irradiated with 80 rad, and the total activity of DNA was determined at 72 hours after synchronization. A significant maximum of recovery was found at 5 hours (S phase) after the administration of hydroxyurea. In similar conditions, the dose-response curves corresponding to the G1, S and M phase of the division cycle were also determined. The synchronization of dividing cells induced by hydroxyurea failed in the spleen.
D000818:Animals; D003037:Cobalt Radioisotopes; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D008297:Male; D051379:Mice; D008938:Mitosis / Q000528:radiation effects*; D013154:Spleen / Q000528:radiation effects; D013950:Thymus Gland / Q000528:radiation effects*
D003037:Cobalt Radioisotopes