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金属代谢问题应包括金属的吸收、分布、组织蓄积、排泄以及在体内的转化等方面的内容。但限于现有的资料,只能讨论金属通过胎盘的转运和金属对哺乳期动物的作用这两个问题。作者总结了金属通过胎盘的转运。以往资料常将初生动物或其组织中的金属含量与母体进行比较,现在人们已经认识到这种比较是有缺陷的。因为金属通过胎盘的转运是随妊娠时间而变化的,而产前某一时期金属的转运可能特别有意义。然而,在人类资料中只能比较脐带血和母血中的金属浓度。动物实验资料表明,某些金属(如三价铬、镉及无机汞)实际上可能不通过胎盘。另外一些金属则可以通过胎盘,因而初生婴儿体内这些金属的含量大致与母体一致。三种汞化合物(甲基汞、苯基汞及汞蒸气)均极易通过胎盘并在胎儿体内蓄积。值得指出的是,尽管已有充
Metabolic problems should include metal absorption, distribution, tissue accumulation, excretion, and the transformation of the body and so on. However, limited to the available information, only the two issues of metal transport through the placenta and the effect of metal on lactating animals can be discussed. The authors conclude the metal transport through the placenta. Previous data often compare the metal content of newborn animals or their tissues to that of the parent, and it has now been recognized that such comparisons are flawed. Because the transport of metal through the placenta varies with time of pregnancy, the transport of metals during a prenatal period may be of particular interest. However, only the concentrations of metals in cord blood and maternal blood can be compared in human data. Experimental animal data suggest that certain metals (such as Cr3 +, Cd and inorganic mercury) may actually not pass through the placenta. Other metals can pass through the placenta, so that the content of these metals in newborn babies roughly consistent with the mother. Three kinds of mercury compounds (methylmercury, phenylmercury and mercury vapor) are very easy to cross the placenta and accumulate in the fetus. It is worth noting that, despite the existing charge,