Acquired Radioresistances after Small Doses of X-rays in Mice

概要

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Preirradiation with 2.5-15 cGy of X-rays two months before a second exposure to a sublethal dose enhanced the survival rate in mice (ICR strain of Charles River Japan, Co.). Optimal and significant increase was observed with 5-10 cGy. The radioresistance was observed both in male and female mice. Time study for inducing radioresistance was carried out using male (from the next day till 2 months after preirradiation with 5 cGy) and female (from 2 months till 5 months). The result showed that the radioresistance was observed 2.0-2.5 months after 5 cGy. The resistance did not appear within 1.5 months, and disappeared after 3 months or more. On the other hand, several authors reported that preirradiation with 50-150 cGy or more resulted in radioresistance about half a month later. We found that preirradiation with 30 or 50 cGy resulted in radioresistance 2 weeks later. This shows that some biological effects may be distinguishable with radiation doses of 5-10 cGy and 30 cGy or more, or that biological effects are quite different with the two dose ranges.
大阪府立大学の論文
1993-03-31