MATERNAL DEHYDRATION--FETAL & AMNIOTIC FLUID HOMEOSTASIS

孕妇可能会接触到运动，热，或 胃肠道（剧吐）水分流失，所有这些通常 诱导血浆渗透压（osm）增加>10 mOsm。 虽然 胎儿血浆依赖于母体OSM， 脱水和随后的补液对胎儿的影响 探讨了 母体血浆osm增加， 生理范围导致显著的胎儿内分泌反应 （精氨酸加压素和肾素分泌的刺激， 可能是心房利钠因子的抑制）， 胎儿水动力学和血容量的改变。 尽管 母体补液、胎儿内分泌和体液反应持续存在 超过回到基础母体和胎儿血浆OSM。 作为 结果，母亲间歇性脱水可能导致 羊水过少、早产和/或胎儿发育 生长迟缓 该项目将长期利用 插管绵羊模型，以研究胎儿和 羊水水电解质反应 脱水和随后的再水化。 房室模型将 用于量化胎儿水获取的变化 （胎儿吞咽和经胎盘血流）和排泄（尿液和 肺液）。 具体来说，我们已经开发并确认了一个 测量胎儿吞咽活动和吞咽量的方法。 将直接测量胎儿尿液和肺液的产生， 并计算经胎盘血流。 对胎儿的影响 血容量以及对羊水和尿囊水的影响 将对隔间进行评估。 所选胎儿的反应 内分泌系统的核心水稳态将被检查， 胎儿体液内分泌调节的机制， 电解质和吞咽反应将使用 选择性激动剂和拮抗剂。 作为母体和胎儿 对再水化的反应不同，取决于 水化，该项目还将检查胎儿的内分泌， 对几种母体补液方法的液体反应。 研究 绵羊模型的脱水和再水化代表了 了解母胎水动力学的有前途的方法， 同时解决围产期的潜在关键问题， 药

Pregnant women may be exposed to exercise, thermal, or gastrointestinal (hyperemesis) water loss, all of which commonly induce a >10 mOsm increase in plasma osmolality (osm). Although fetal plasma is dependent on maternal osm the impact of maternal dehydration and subsequent rehydration on the fetus has not been explored. Increases in maternal plasma osm well within the physiologic range result in significant fetal endocrine responses (stimulation of arginine vasopressin and renin secretion and perhaps a suppression of atrial natriuretic factor) and subsequent alterations in fetal water dynamics and blood volume. Despite maternal rehydration, fetal endocrine and fluid responses persist beyond a return to basal maternal and fetal plasma osm. As a result, episodic maternal dehydration may contribute to the development of oligohydramnios, premature labor, and/or fetal growth retardation. This project will utilize the chronically catheterized ovine model to investigate the ontogeny of fetal and amniotic fluid water and electrolyte responses to maternal dehydration and subsequent rehydration. A compartmental model will be utilized to quantify alterations in fetal water acquisition (fetal swallowing and transplacental flow) and excretion (urine and lung fluid). Specifically, we have developed and confirmed a method for the measurement of fetal swallowing activity and volume. Fetal urine and lung fluid production will be measured directly, and transplacental flow calculated. The resultant effects on fetal blood volume and the impact on amniotic and allantoic water compartments will be evaluated. The response of selected fetal endocrine systems central to water homeostasis will be examined and the mechanisms of endocrine regulation of fetal fluid and electrolytes and swallowing responses will be studied using selective agonists and antagonists. As maternal and fetal responses to rehydration differ depending upon the mode of hydration, this project also will examine the fetal endocrine and fluid responses to several means of maternal rehydration. Studies of dehydration and rehydration of the ovine model represent a promising approach to understanding maternal-fetal water dynamics, while addressing a potentially critical problem in perinatal medicine.