小剂量氚水诱发小鼠骨髓细胞遗传学适应性反应

CYTOGENETIC ADAPTIVE RESPONSE OF MOUSE BONE MARROW CELLS TO LOW LEVEL HTO

小鼠腹腔注射3.7×10~2—3.7×10~5Bq/gbw HTO(氚水)作为适应剂量,随后全身照射1.5Gy^(60)Coγ射线作为激发剂量,观察对骨髓细胞染色单体畸变率的影响。结果表明:以3.7×10~3Bq/gbwHTO组诱发的适应性反应最明显,当高达3.7×10~5Bq/gbw时适应性反应似乎消失;在腹腔注射3.7×10~3Bq/gbw后,1—5d内照射激发剂量1.5Gy均可观察到适应性反应,以第5d最显著,观察值相当于预期值的50％,至第7d时观察值接近于预期值;照射激发剂量后随着时间的延长染色单体畸变率逐渐降低,如果以适应性反应指数表示,激发剂量照射后24h达最大值0.52。

Mice were abdominally injected with a adaptive dose of 3.7×10~2--3.7×10~5 Bq/gbw HTO, and then exposed to a challenge dose of 1.5 Gy of^(60)Coγ-rays. In bone marrow cells that received both the adaptive and challenge doses.the chromatid breaks are lower than expected on the basis of additivity of the effec-ts of the individual treatment. The adaptive response induced with 3.7×10~3 Bq/gbwHTO is the most remarkable, but at 3.7×10~5 Bq/gbw the adaptive response seems tobe disappear. The adaptive response can be observed by exposing to 1.5 Gy γ-raysfrom 1 to 5 days after injection of 3.7×10~3 Bq/gbw HTO, which is the most obvi-ous at the 5 th day, to reduce chromatid breaks to 50% of expected, but at the 7 thday to equat to expected. The frequency of chromatid braeks is gradually reducedwith time after challenge dose. the maximum index number of adaptive response is0.50 and appears at 24 hr after challenge dose.