EXPERIMENTAL POLYHYDRAMNIOS AND HYDROPS FETALIS

最一致和最有力的胎儿心血管反应发生在 胎儿（租赁）动脉血压的防御，如引出的， 例如，胎儿主动脉的肾上性狭窄。 部分 反应是激活胎儿的肾素血管紧张素系统。 当 血管紧张素以非常低的剂量长期输注到正常胎儿中 率，有一个缓慢发展，但非常大的增加，胎儿 动脉血压 但是胎盘的数量也有很大的增加， 水转移到胎儿，如羊水过多所证明的完整的 肾切除胎儿中的胎儿和胎儿积水。 是 因此，假设胎盘水转移的调节 从母体进入孕体是体内平衡机制的一部分 控制胎儿动脉压羊水过多和水肿 是体内平衡机制的脱轨 拟议实验的具体目标是，首先，解开 在胎盘内起作用的生理调节机制， 控制水转移，第二，量化相关的血液动力学 和膜参数。 带留置导管的胎羊， 将使用电子仪器。 胎盘流量和压力 将在存在部分静脉阻塞的情况下测量， 而不伴随施用血管紧张素。 我们研究计划的长期目标是帮助澄清 人类羊水过多的病理生理学，一种常见的妊娠疾病， 和胎儿水肿，一种罕见但通常致命的疾病， 新生儿

The most consistent and vigorous fetal cardiovascular response occurs in the defense of fetal (rental) arterial blood pressure, as elicited, for instance, by supra-renal stenosis of the fetal aorta. Part of this response is the activation of the fetal renin angiotensin system. When angiotensin is chronically infused into normal fetuses, at very low dose rates, there is a slowly developing but very large increase in fetal arterial blood pressure. But there is also a great increase in placental water transfer into the fetus, as evidenced by polyhydramnios in intact fetuses and hydrops fetalis in nephrectomized fetuses. It is hypothesized, therefor, that the modulation of placental water transfer from the mother into the conceptus is part of the homeostatic mechanism that controls fetal arterial pressure and that polyhydramnios and hydrops are derailments of that homeostatic mechanism. Specific aims of the proposed experiments are, first, to unravel the physiological regulation mechanism that acts within the placenta to control water transfer and, second, to quantify the relevant hemodynamic and membrane parameters. Fetal sheep with indwelling catheters and electronic instrumentation will be used. Placental flows and pressures will be measured in the presence of partial venous obstruction with and without the concomitant administration of angiotensin. The long-term goal of our research program is to help clarify the pathophysiology of human polyhydramnios, a common disease of pregnancy, and of hydrops fetalis, an uncommon but usually fatal disease of the newborn.