Takahashi S, Sato H, Kubota Y, Inaba J
Division of Comparative Radiotoxicology, National Institute of Radiological Sciences, Chiba, Japan.
J Radiat Res. 1992 Dec;33(4):301-8. doi: 10.1269/jrr.33.301.
The 239Pu distribution in the 12.5-day-old rat conceptus was compared between in vivo and in vitro experimental systems to establish a possible mechanism of cross-placental transfer of this radionuclide. In the in vivo study, plutonium citrate solution was injected intravenously to pregnant Wistar rats. In the in vitro study, either plutonium citrate or plutonium hydroxide colloid was administered, as a solution of Eagle MEM and FCS containing 239Pu at the concentration used in the maternal serum in the in vivo experiments, to rat conceptuses maintained by the whole-embryo culture method. The concentration of 239Pu in the yolk sac (239Pu activity per gram wet weight) were much higher than in the embryo in both the in vivo and in vitro experiments, suggesting that the yolk sac may be an effective barrier against the transfer of plutonium to the embryos. The ratios of the 239Pu concentration in the yolk sac to that in the embryo were relatively constant with time after administration in the in vitro system; 18-27 for plutonium citrate and 67-84 for plutonium hydroxide. In the in vivo experiment, these ratios changed with time after injection; 15 at 5 min and 62 and 60 min after injection. This suggests that in the in vivo system, the chemical form of 239Pu changed with time after injection, probably to a macromolecular form such as the hydroxide colloid or plutonium-protein complex although 239Pu was injected to the maternal blood as citrate.
比较了12.5日龄大鼠胚胎中239Pu在体内和体外实验系统中的分布情况，以确定这种放射性核素跨胎盘转移的可能机制。在体内研究中，向怀孕的Wistar大鼠静脉注射柠檬酸钚溶液。在体外研究中，将柠檬酸钚或氢氧化钚胶体作为含有239Pu的伊格尔MEM和胎牛血清溶液给予采用全胚胎培养法维持的大鼠胚胎，其浓度与体内实验中母体血清中的浓度相同。在体内和体外实验中，卵黄囊中239Pu的浓度（每克湿重的239Pu活性）均远高于胚胎中的浓度，这表明卵黄囊可能是钚向胚胎转移的有效屏障。在体外系统中，给药后卵黄囊中239Pu浓度与胚胎中239Pu浓度的比值随时间相对恒定；柠檬酸钚为18 - 27，氢氧化钚为67 - 84。在体内实验中，这些比值在注射后随时间变化；注射后5分钟为15，注射后62分钟和60分钟分别为62和60。这表明在体内系统中，239Pu的化学形式在注射后随时间发生了变化，尽管239Pu是以柠檬酸盐形式注入母体血液的，但可能变成了大分子形式，如氢氧化胶体或钚 - 蛋白质复合物。
