Mann S E, Nijland M J, Ross M G
Department of Obstetrics and Gynecology, University of California Los Angeles School of Medicine, Harbor-UCLA Medical Center, Torrance 90502, USA.
J Soc Gynecol Investig. 1999 Sep-Oct;6(5):252-7. doi: 10.1016/s1071-5576(99)00032-5.
Amniotic fluid (AF) volume and composition are maintained by a balance of fetal fluid production and resorption. Ovine fetal resorption of peptide hormones (e.g., arginine vasopressin) from the amniotic cavity has been demonstrated, with resultant effects on fetal urine production. The present study was undertaken to determine whether intra-amniotically administered steroid hormones could be absorbed from the amniotic cavity into fetal plasma and whether intra-amniotic aldosterone administration would affect fetal renal sodium and potassium excretion.
Seven singleton fetuses (132 +/- 2 days) were prepared with bladder, vascular, and amniotic cavity catheters. After a 5-day recovery period, a bolus of aldosterone was injected into the amniotic cavity. Fetuses were monitored for an additional 24 hours during which time maternal, fetal, and AF samples were collected at timed intervals.
After intra-amniotic aldosterone injection, AF aldosterone concentrations increased at 30 minutes and remained elevated for 4 hours after the aldosterone bolus. In response to increased AF aldosterone, fetal plasma aldosterone levels significantly increased by 30 minutes, peaked at 1 hour (17 +/- 4 to 758 +/- 160 pg/mL), and remained elevated for a minimum of 4 hours. Fetal urine sodium excretion significantly decreased and potassium excretion increased. Maternal plasma aldosterone levels increased significantly (25 +/- 10 to 401 +/- 56 pg/mL) but to levels below fetal values. Amniotic fluid and fetal and maternal aldosterone concentrations and fetal urine sodium and potassium excretion returned toward basal levels by 24 hours.
The steroid hormone aldosterone can be absorbed from the amniotic cavity into the fetal circulation and can alter fetal urine electrolyte excretion. These results suggest that the amniotic cavity is a potential route of in utero pharmacologic fetal therapy.
羊水（AF）的容量和成分通过胎儿液体生成与重吸收之间的平衡得以维持。已证实绵羊胎儿可从羊膜腔重吸收肽类激素（如精氨酸加压素），进而影响胎儿尿液生成。本研究旨在确定羊膜腔内给予的甾体激素能否从羊膜腔吸收进入胎儿血浆，以及羊膜腔内给予醛固酮是否会影响胎儿肾脏的钠和钾排泄。
对7只单胎胎儿（132±2天）植入膀胱、血管和羊膜腔导管。经过5天的恢复期后，向羊膜腔内注射一剂醛固酮。对胎儿进行额外24小时的监测，在此期间按预定时间间隔采集母体、胎儿和羊水样本。
羊膜腔内注射醛固酮后，羊水醛固酮浓度在30分钟时升高，并在注射醛固酮推注后持续升高4小时。作为对羊水醛固酮升高的反应，胎儿血浆醛固酮水平在30分钟时显著升高，在1小时时达到峰值（从17±4至758±160 pg/mL），并至少持续升高4小时。胎儿尿钠排泄显著减少，钾排泄增加。母体血浆醛固酮水平显著升高（从25±10至401±56 pg/mL），但低于胎儿水平。羊水以及胎儿和母体的醛固酮浓度以及胎儿尿钠和钾排泄在24小时时恢复至基础水平。
甾体激素醛固酮可从羊膜腔吸收进入胎儿循环，并可改变胎儿尿液电解质排泄。这些结果表明羊膜腔是子宫内胎儿药物治疗的一条潜在途径。
