Atkinson D E, Robinson N R, Sibley C P
Department of Child Health, The University of Manchester, St. Mary's Hospital, United Kingdom.
Am J Physiol. 1991 Dec;261(6 Pt 2):R1461-4. doi: 10.1152/ajpregu.1991.261.6.R1461.
To investigate how the passive permeability of the rat placenta changes during the last third of gestation we measured the unidirectional maternofetal clearance (Kmf) of three polar nonelectrolytes. We found that Kmf (microliters.min-1.g placenta-1) for all three tracers increased between days 15 and 22 (term is 23 days). The increase was less for the largest tracer, [14C]inulin (3.5-fold increase from 0.5 +/- 0.1 to 1.6 +/- 0.1 microliters.min-1.g placenta-1), than for the smaller tracers, [14C]mannitol (7-fold increase from 1.6 +/- 0.1 to 10.9 +/- 0.4 microliters.min-1.g placenta-1) and 51Cr-labeled EDTA (9.5-fold increase from 0.8 +/- 0.04 to 7.6 +/- 0.7 microliters.min-1.g placenta-1). These data suggest that whilst the overall permeability of the rat placenta increases during this period of pregnancy, restriction to the diffusion of large (greater than or equal to 1.5 nm molecular radius) polar nonelectrolytes also increases.
为了研究大鼠胎盘的被动通透性在妊娠最后三分之一阶段如何变化，我们测量了三种极性非电解质的单向母胎清除率（Kmf）。我们发现，在第15天至第22天（足月为23天）期间，所有三种示踪剂的Kmf（微升·分钟⁻¹·克胎盘⁻¹）均有所增加。最大的示踪剂[¹⁴C]菊粉的增加幅度较小（从0.5±0.1微升·分钟⁻¹·克胎盘⁻¹增加到1.6±0.1微升·分钟⁻¹·克胎盘⁻¹，增加了3.5倍），而较小的示踪剂[¹⁴C]甘露醇（从1.6±0.1微升·分钟⁻¹·克胎盘⁻¹增加到10.9±0.4微升·分钟⁻¹·克胎盘⁻¹，增加了7倍）和⁵¹Cr标记的乙二胺四乙酸（从0.8±0.04微升·分钟⁻¹·克胎盘⁻¹增加到7.6±0.7微升·分钟⁻¹·克胎盘⁻¹，增加了9.5倍）的增加幅度更大。这些数据表明，虽然大鼠胎盘的总体通透性在孕期这个阶段有所增加，但对大（分子半径大于或等于1.5纳米）极性非电解质扩散的限制也在增加。
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