Dale P S, McNaughton T G, Power L A, Gilbert R D, Power G G
Department of Physiology, Loma Linda University, School of Medicine, California 92350.
Am J Physiol. 1990 Apr;258(4 Pt 2):R889-94. doi: 10.1152/ajpregu.1990.258.4.R889.
An investigation of the site and mechanism responsible for the maternal-fetal electrical potential difference (PD) was done in 11 anesthetized guinea pigs at 54-56 days gestation. We removed the most distal fetus and placenta from one uterine horn and secured a catheter, thermistor, and Ag-AgCl electrode in the resulting pouch. The pouch was filled with Earle's solution. We placed another thermistor and electrode in the maternal abdomen. The PD between electrodes was monitored continuously; periodic samples of maternal blood and intrauterine fluid were taken. Thirty minutes after the uterus was filled, the PD (uterine cavity negative) averaged 29.6 +/- 4.5 (95% confidence interval of the mean) mV. Over 4 h, intrauterine K+ concentration [( K+]) decreased from 4.9 to 2.6 +/- 0.5 meq/l, against a chemical and electrical gradient. In eight animals, we measured bidirectional Na+ flux using 22Na and 24Na. The flux ratio was not distinguishable from unity despite a significant PD. Our data indicate that the maternal-fetal PD is probably generated by the endometrial epithelium and that Na+ and K+ both move across the epithelium by active transport or cotransport rather than simple diffusion.
对11只处于妊娠54 - 56天的麻醉豚鼠进行了母体 - 胎儿电位差（PD）产生部位及机制的研究。我们从一个子宫角取出最远端的胎儿和胎盘，在剩余的囊袋中固定一根导管、一个热敏电阻和一个银 - 氯化银电极。囊袋中充满厄尔氏溶液。我们在母体腹部放置了另一个热敏电阻和电极。持续监测电极之间的PD；定期采集母体血液和子宫内液体样本。子宫充满后30分钟，PD（子宫腔为负）平均为29.6±4.5（均值的95%置信区间）mV。在4小时内，子宫内K⁺浓度[K⁺]从4.9降至2.6±0.5 meq/l，这是逆着化学和电势梯度的。在8只动物中，我们使用²²Na和²⁴Na测量了双向Na⁺通量。尽管存在显著的PD，但通量比与1没有差异。我们的数据表明，母体 - 胎儿PD可能由子宫内膜上皮产生，并且Na⁺和K⁺都是通过主动转运或协同转运而非简单扩散穿过上皮的。
