Acquired radioresistance after low dose X-irradiation in mice.
Low doses (2.5-15 cGy) of X-irradiation two months prior to a second exposure to a sublethal dose enhanced the survival rate in mice. Optimal and significant increase was observed with 5-10 cGy. Endogenous spleen colony counts (endo-CFUs) after 7 Gy increased by a factor of about 1.7 in mice pre-irradiated with 5-10 cGy, while the number of blood forming stem cells (CFUs) in the pre-irradiated group did not exceed that in the sham-irradiated control group at the period of the second exposure (two months after irradiation with 5 cGy). The low dose exposure seems to stimulate recovery of blood forming stem cells after the second irradiation and favors a decrease in the incidence of bone marrow death.
Yonezawa
M
M
Department of Medical Biology and Hygiene, Osaka Prefectural Radiation Research Institute, Japan.
Takeda
A
A
Misonoh
J
J
D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D006412:Hematopoietic Stem Cells / Q000528:radiation effects; D051379:Mice; D008813:Mice, Inbred ICR; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental; D011836:Radiation Tolerance; D013154:Spleen / Q000166:cytology / Q000528:radiation effects; D015996:Survival Rate; D014916:Whole-Body Irradiation