Gilbert W M, Cheung C Y, Brace R A
Department of Reproductive Medicine, University of California, San Diego.
Am J Obstet Gynecol. 1991 Apr;164(4):1013-8; discussion 1018-20. doi: 10.1016/0002-9378(91)90576-d.
Recently an intramembranous pathway was reported in the ovine fetus as a route for the movement of a significant volume of water from the amniotic cavity directly into the fetal blood, which perfuses the fetal membranes and fetal surface of the placenta. To test whether this pathway could be an avenue for the movement of arginine vasopressin from the amniotic cavity into the fetal circulation, we injected 1 to 25 micrograms of arginine vasopressin into the amniotic cavity of two groups of chronically catheterized fetal sheep: a control group of seven animals and a group of seven animals with surgical ligation of the fetal esophagus. We found similar and highly significant increases of arginine vasopressin concentrations in both control and surgically ligated fetuses in amniotic fluid (p less than 0.00001), fetal plasma (p less than 0.0001), and fetal urine (p less than 0.0001). Both groups had similar increases in arterial (p less than 0.0001) and venous (p less than 0.003) pressures with simultaneous decreases in urine flow (p less than 0.001) and heart rate (p less than 0.0001) after the intraamniotic injection of arginine vasopressin. We conclude that amniotic arginine vasopressin can be rapidly absorbed in its biologically active form directly into the fetal circulation through the intramembranous pathway. Furthermore, the observation that esophageal ligation did not alter this absorption suggests that the intramembranous pathway may be important in the regulation of amniotic fluid volume and composition.
最近有报道称，在绵羊胎儿中存在一种膜内途径，大量水分可通过该途径从羊膜腔直接进入胎儿血液，而胎儿血液会灌注胎膜和胎盘的胎儿表面。为了测试该途径是否可能是精氨酸加压素从羊膜腔进入胎儿循环的通道，我们向两组长期插管的胎羊的羊膜腔内注射了1至25微克精氨酸加压素：一组为7只动物的对照组，另一组为7只手术结扎胎儿食管的动物组。我们发现，对照组和手术结扎的胎儿的羊水（p<0.00001）、胎儿血浆（p<0.0001）和胎儿尿液（p<0.0001）中精氨酸加压素浓度均有相似且极显著的升高。羊膜腔内注射精氨酸加压素后，两组的动脉压（p<0.0001）和静脉压（p<0.003）均有相似的升高，同时尿流量（p<0.001）和心率（p<0.0001）下降。我们得出结论，羊膜中的精氨酸加压素可以以其生物活性形式通过膜内途径迅速被吸收直接进入胎儿循环。此外，食管结扎并未改变这种吸收的观察结果表明，膜内途径可能在羊水容量和成分的调节中起重要作用。
