NEURAL CONTROL OF THE CIRCULATION IN PREGNANCY

在人类和大多数动物模型(包括大鼠)中，正常妊娠 其特点是血容量和心输出量增加，以及 降低动脉血压和总外周阻力。肾素 和前列腺素合成在怀孕期间增加。有趣的是， 怀孕与加压反应降低有关 外源性应用升压剂：一种逆转的效果 在阻止前列腺素合成之后。显然，重大改建 在神经-体液循环控制中，有必要 适应正常妊娠的血流动力学特征。然而，几乎没有人 已有研究对心血管反射机制进行了研究 在怀孕期间。当前提案的总体目标是测试 怀孕期间适应发生在神经中的一般假设 在压力感受器水平上的循环控制，中央 神经系统和外周血管系统对 正常妊娠的血流动力学特征。这些改编 可能与血容量的变化，前列腺素的产生， 和/或反射系统之间的相互作用的变化。实验是 计划在三组大鼠中-未怀孕，中期-怀孕 (黄体酮占优势)和晚孕(雌激素占优势)--以及 将进行比较，以确定怀孕对以下方面的影响： 单一单位传入动脉压力感受器放电及其影响 阻断前列腺素合成；动脉和心肺 压力感受性反射对传出局部交感神经活动的控制 心肺的容量和化学(前列腺素)敏感性 受体；3)反射控制的副交感和交感成分 心率；4.)压力感受性反射对子宫血管阻力的控制 子宫的传出交感神经活动；传出 心血管相关中枢神经系统激活的反应 网站。这些实验将为可能的机制提供新的信息 用于妊娠的心血管适应。此外，由于故障 的正常适应与严重的病理状态有关 如妊娠高血压综合征，这些研究将提供有价值的 临床适用的信息。

In both humans and most animal models (including the rat), normal pregnancy is characterized by increased blood volume and cardiac output, and decreased arterial blood pressure and total peripheral resistance. Renin and prostanoid synthesis are increased during pregnancy. Interestingly, pregnancy is associated with decreased pressor responsiveness to exogenously administered pressor agents: an effect which is reversed following blockade of prostaglandin synthesis. Obviously, major alterations in the neural-humoral control of the circulation would be necessary to accommodate the hemodynamic profile of normal pregnancy. However, few studies exist in which cardiovascular reflex mechanisms have been examined in pregnancy. The overall goal of the current proposal is to test the general hypothesis that during pregnancy adaptations occur in the neural control of the circulation at the level of the baroreceptors, the central nervous system and the peripheral vasculature which contribute to the hemodynamic profile characteristic of normal pregnancy. These adaptations could be related to the changes in blood volume, prostanoid production, and/or changes in the interaction between reflex systems. Experiments are planned in three groups of rats - nonpregnant, midterm-pregnant (progesterone dominant), and late-pregnant (estrogen dominant) - and comparisons will be made to determine the effects of pregnancy on: 1.) single unit afferent arterial baroreceptor discharge and the effects of blockade of prostanoid synthesis; 2.) arterial and cardiopulmonary baroreflex control of efferent regional sympathetic nerve activity and both the volume and chemical (prostanoids) sensitivity of cardiopulmonary receptors; 3.) parasympathetic and sympathetic components of reflex control of heart rate; 4.) baroreflex control of uterine vascular resistance and efferent sympathetic nerve activity to the uterus; and 5.) efferent responses to activation of cardiovascular related central nervous system sites. These experiments will yield new information on possible mechanisms for the cardiovascular adaptations of pregnancy. In addition, since failure of the normal adaptations is associated with serious pathological states such as pregnancy-induced hypertension, these studies will provide valuable clinically applicable information.