EXPERIMENTAL POLYHYDRAMNIOS AND HYDROPS FETALIS

最一致和最强烈的胎儿心血管反应发生在 胎儿(租借)动脉血压的防御，如引起的， 例如，胎儿主动脉肾上狭窄。其中的一部分 反应是胎儿肾素血管紧张素系统的激活。什么时候 血管紧张素以极低的剂量长期注入正常胎儿体内 比率，有一个缓慢的发展，但非常大的增加胎儿 动脉血压。但胎盘也有很大的增加 羊水过多可见羊水进入胎儿体内 肾切除胎儿中的胎儿和胎儿积水。它是 因此，假设胎盘水分转移的调节 从母亲到受孕是动态平衡机制的一部分 控制胎儿动脉压以及羊水过多和积水 是动态平衡机制的脱轨。 拟议中的实验的具体目标是，首先，揭开 在胎盘内起作用的生理调节机制 控制水的转移，第二，量化相关的血流动力学 和膜参数。留置导尿管的胎羊和 将使用电子仪器。胎盘流动和压力 在存在部分静脉阻塞的情况下进行测量 而不需要同时服用血管紧张素。 我们研究计划的长期目标是帮助澄清 妊娠常见疾病--羊水过多的病理生理学 以及胎儿积水，这是一种不常见但通常致命的疾病 刚出生的。

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.