“Radiation Hormesis”中的剂量率效应

为了揭示不同剂量率Ｘ射线低剂量全身照射对低剂量辐射兴奋效应（ＲａｄｉａｔｉｏｎＨｏｒｍｅｓｉｓ）的影响，采用不同剂量率（１２．７ｍＧｙ／ｍｉｎ和０．２Ｇｙ／ｍｉｎ）对Ｂａｌｂ／ｃ小鼠进行低剂量全身照射，研究了低剂量辐射兴奋效应中的剂量率效应。结果表明：采用不同剂量率Ｘ射线照射同一剂量时，所引起的生物效应不同。剂量率为１２．７ｍＧｙ／ｍｉｎ时，脾细胞３Ｈ－ＴｄＲ参入量对ＣｏｎＡ的反应性明显增强，尤其以７６．７ｍＧｙ和１０５．５ｍＧｙ照射组最为显著（Ｐ＜０．０１），表现出明显的辐射免疫兴奋效应。而剂量率为０．２Ｇｙ／ｍｉｎ时，在１０５．５ｍＧｙ以内，脾细胞３Ｈ－ＴｄＲ参入量对ＣｏｎＡ的反应性无明显变化。该结果提示：高剂量率低剂量全身照射不能引起低剂量辐射兴奋效应。

Influence of dose rate on radiation hormesis with low dose exposure

In order to explore the influence of dose rate on radiation hormesis after low dose irradiation,Balb/c mice were irradiated at a same total dose with dose rates of 12.7 mGy/min and 0.2 Gy/min.The results showed that different biological effects were induced by different dose rates at the same dose .The response of splenic lymphocytes to Con A assessed by 3H-TdR incorporation was increased after irradiation with a dose rate of 12.7 mGy/min,which is especially marked following total doses of 76.7 mGy and 105.5 mGy ( P <0 01).However,the response of splenic lymphocytes to Con A showed no significant changes after irradiation with a dose rate of 0.2 mGy/min at the same total dose.The result indicated that low dose radiation hormesis could not be induced by high dose rate X-rays.