测量液体经胎盘向胎羊的净转运。
Measurement of net transplacental transfer of fluid to the fetal sheep.
作者信息
Lumbers E R, Smith F G, Stevens A D
出版信息
J Physiol. 1985 Jul;364:289-99. doi: 10.1113/jphysiol.1985.sp015745.
If fetal drinking activity is prevented and it is assumed that in the latter third of gestation the fetus is capable of maintaining itself in fluid balance, then the net amount of fluid gained across the placenta by the fetus is equal to the amount of fluid lost from the fetus, by routes other than the placenta, plus fluid deposited in growing tissues minus the amount of water produced as a result of oxidative metabolism. Net transplacental transfer of fluid to the fetus over a 3 h period was measured in eight chronically catheterized fetal sheep in which drinking activity was prevented by ligating the oesophagus. Urine and lung liquid flow rates were measured. In the latter third of gestation, these are the only significant sources of fluid loss from these fetuses during the 3 h experimental period. Water produced as a result of oxidative metabolism was calculated, as was the amount of fluid deposited in growing tissues during the course of the experiment. The weight of the fetus at the beginning of the experiment and the change in weight that occurred during the experiment was calculated by measuring the weight of the fetus at death (within 30 h) and applying an equation which describes the body weight-gestation age relationship for merino sheep. Net transplacental fluid transfer was 0.40 +/- 0.09 ml min-1 kg-1 (range 0.30-0.54 ml min-1 kg-1). Fetal urine flow rate averaged 0.30 +/- 0.11 ml min-1 kg-1. It was 72.8 +/- 10.0% of the volumes used to calculate net transplacental fluid transfer to the fetus. Lung liquid flow rate was 0.079 +/- 0.039 ml min-1 kg-1. It was 20.2 +/- 9.2% of the volumes used to calculate net fluid intake. The amount of fluid deposited as a result of tissue growth was 0.023 +/- 0.001 ml min-1 kg-1; it was 5.94 +/- 1.1% of the volumes used in the equation, while the production of water as a result of metabolism was 3.9 X 10(-3) ml min-1 kg-1 (Conrad & Faber, 1977) and constituted 1.01 +/- 0.22% of the volumes used in the equation. This method of measuring net transplacental fluid transfer to the fetus can be used to measure fetal fluid intake over relatively short periods of time. It also means that the effects of disturbances in maternal fluid and electrolyte balance on fluid transfer to the fetus can be studied and quantitated.
如果胎儿的饮水活动被阻止，并且假设在妊娠后期胎儿能够维持自身的水平衡，那么胎儿通过胎盘获得的净液量等于胎儿通过胎盘以外的途径丢失的液量，加上沉积在生长组织中的液体量减去氧化代谢产生的水量。在八只长期插管的胎儿绵羊中测量了3小时内液体向胎儿的经胎盘净转运，这些胎儿的饮水活动通过结扎食管来阻止。测量了尿液和肺液流速。在妊娠后期，这些是在3小时实验期间这些胎儿液体流失的唯一重要来源。计算了氧化代谢产生的水量以及实验过程中沉积在生长组织中的液体量。通过测量胎儿死亡时（30小时内）的体重并应用描述美利奴羊体重与妊娠年龄关系的方程，计算了实验开始时胎儿的体重以及实验期间发生的体重变化。经胎盘净液体转运为0.40±0.09毫升·分钟⁻¹·千克⁻¹（范围为0.30 - 0.54毫升·分钟⁻¹·千克⁻¹）。胎儿尿流率平均为0.30±0.11毫升·分钟⁻¹·千克⁻¹。它占用于计算经胎盘向胎儿净液体转运量的72.8±10.0%。肺液流速为0.079±0.039毫升·分钟⁻¹·千克⁻¹。它占用于计算净液体摄入量的20.2±9.2%。由于组织生长而沉积的液体量为0.023±0.001毫升·分钟⁻¹·千克⁻¹；它占方程中使用量的5.94±1.1%，而代谢产生的水量为3.9×10⁻³毫升·分钟⁻¹·千克⁻¹（康拉德和法伯，1977年），占方程中使用量的1.01±0.22%。这种测量经胎盘向胎儿净液体转运的方法可用于测量相对短时间内胎儿的液体摄入量。这也意味着可以研究和量化母体液体和电解质平衡紊乱对向胎儿液体转运的影响。
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