Weedon A P, Stacey T E, Ward R H, Boyd R D
Am J Physiol. 1978 Dec;235(6):F536-41. doi: 10.1152/ajprenal.1978.235.6.F536.
Conscious pregnant sheep in the last 3 wk of gestation were studied 1--3 days after surgery. Fetal plasma sodium concentration was significantly lower than maternal. A mean electrical potential difference (PD) of 34 +/- 4 (SE) mV (n = 24) was recorded between maternal and fetal intravascular catheters, the mother being positive with reference to fetus. Unidirectional fetomaternal (Jf leads to m) and maternofetal (Jm leads to f) sodium fluxes were determined by application of Fick's principle to uterine and umbilical circulations following injection of 22NaCl or 24NaCl to fetus or mother, respectively. Blood flows were measured by an antipyrine technique. Jm leads to f = 0.142 +/- 0.029 mmol/min (n = 10); Jf leads to m =0.137 +/- 0.015 mmol/min (n = 21). Jm leads to f increased as a linear function of calculated fetal weight. In seven sheep both Jm leads to f and Jf leads to m were measured in a single experiment. The measured ratio Jm leads to f/Jf leads to m was significantly different from the ratio predicted using Ussing's flux ratio equation. There is probably a transplacental sodium pump active in the direction fetus to mother.
对妊娠最后3周的清醒怀孕绵羊在手术后1 - 3天进行了研究。胎儿血浆钠浓度显著低于母体。在母体和胎儿血管内导管之间记录到平均电位差（PD）为34±4（SE）mV（n = 24），母体相对于胎儿为正。分别向胎儿或母体注射²²NaCl或²⁴NaCl后，通过将菲克原理应用于子宫和脐循环来测定单向胎儿 - 母体（Jf→m）和母体 - 胎儿（Jm→f）钠通量。通过安替比林技术测量血流量。Jm→f = 0.142±0.029 mmol/min（n = 10）；Jf→m = 0.137±0.015 mmol/min（n = 21）。Jm→f作为计算出的胎儿体重的线性函数而增加。在7只绵羊中，在单个实验中测量了Jm→f和Jf→m。测量的Jm→f/Jf→m比值与使用乌斯通量比方程预测的比值显著不同。可能存在一个从胎儿到母体方向活跃的胎盘钠泵。
