绵羊体内水的胎盘外转运

Extraplacental transfer of water in the sheep.

作者信息

Anderson D F, Faber J J, Parks C M

机构信息

Department of Physiology, School of Medicine, Oregon Health Sciences University, Portland 97201.

出版信息

J Physiol. 1988 Dec;406:75-84. doi: 10.1113/jphysiol.1988.sp017369.

DOI:10.1113/jphysiol.1988.sp017369

PMID:3254422

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1191088/

Abstract

Ten pregnant ewes were operated on at 130 days of gestation. The fetal trachea was intubated with a double-lumen tube, an inflatable occluder was placed around the umbilical cord, vascular catheters were placed in the fetal carotid artery and jugular vein and in the maternal jugular vein, and multiple catheters were placed in the amniotic and allantoic sacs. 2. At 139 days gestation, the fetus was ventilated in utero, and the umbilical cord was occluded. The extrafetal fluids were circulated by means of roller pumps. Known activities of radio-iodinated human serum albumin, tritium-labelled water and 14C-labelled urea were injected into the amniotic and/or allantoic fluids. Samples were obtained at 30 min intervals for several hours. 3. Extrafetal fluid volumes were calculated from the albumin distribution volumes. The amounts of labelled water transferred to the maternal circulation were calculated from the changes in tracer concentrations in extrafetal fluids and fetal plasma. 4. No labelled albumin was detected in fetal or maternal plasma. The permeability-surface area product of labelled water at the combined amniotic and allantoic interfaces with the ewe was 28.2 +/- 2.8 ml/min (mean +/- S.E.M.). In five preparations the values could be separately calculated for amniotic and allantoic interfaces. The two mean values (19 +/- 4 and 12 +/- 1 ml/min) were not significantly different from each other. The permeability-surface area product at the combined interfaces with the fetus was 0.96 +/- 0.17 ml/min. Urea was so much less permeable than water that no reliable permeability-surface area products could be calculated in all of the preparations. 5. We calculated that the hydraulic conductivity of the combined extraplacental pathway is more than 0.5% of that of the placenta. Because the osmotic gradient across the extraplacental pathway is one to two orders of magnitude greater than that across the placenta, extraplacental transfer of water can significantly affect intrauterine water volume.

摘要

十只妊娠母羊在妊娠130天时接受手术。用双腔管对胎儿气管进行插管，在脐带周围放置可充气封堵器，在胎儿颈动脉和颈静脉以及母羊颈静脉中放置血管导管，并在羊膜囊和尿囊内放置多个导管。2. 在妊娠139天时，对子宫内的胎儿进行通气，并阻断脐带。通过滚压泵使胎儿外液体循环。将已知活性的放射性碘化人血清白蛋白、氚标记水和14C标记尿素注入羊膜液和/或尿囊液中。每隔30分钟采集样本，持续数小时。3. 根据白蛋白分布容积计算胎儿外液体量。根据胎儿外液体和胎儿血浆中示踪剂浓度的变化计算转移至母体循环的标记水量。4. 在胎儿或母体血浆中未检测到标记白蛋白。羊膜和尿囊与母羊的联合界面处标记水的通透表面积乘积为28.2±2.8毫升/分钟（平均值±标准误）。在五个样本中，可以分别计算羊膜和尿囊界面的值。两个平均值（19±4和12±1毫升/分钟）彼此无显著差异。与胎儿的联合界面处的通透表面积乘积为0.96±0.17毫升/分钟。尿素的通透性比水低得多，以至于在所有样本中都无法计算出可靠的通透表面积乘积。5. 我们计算出胎盘外联合途径的水力传导率超过胎盘的0.5%。由于胎盘外途径的渗透梯度比胎盘途径的渗透梯度大一个至两个数量级，胎盘外的水转移可显著影响子宫内水量。