VASOPRESSIN, ACTH AND RENIN SECRETION DURING PREGNANCY

在怀孕期间，血容量增加了30%-40%，尽管 维持增长的机制(S)尚不清楚。 在正常未怀孕的成年人中，压力感受器反射起着非常重要的作用 在血容量调节中起着重要作用。在这个系统中 血压和血容量的增加(通过伸展感觉 受体位于心脏、颈动脉窦、主动脉弓肾) 抑制容量保留荷尔蒙的产生 血管加压素、促肾上腺皮质激素和血管紧张素II(通过肾素)。因为 妊娠血容量的增加似乎是 保持体内平衡，这项提案试图测试 假设压力感受器反射控制这些激素和 其他心血管参数在怀孕状态下会发生变化 以维持过剩的交易量。此外，血管紧张素II还有 已被证明参与了血液的压力感受性反射调节 血压、心率、心输出量、加压素和促肾上腺皮质激素 分泌物。这项提案的第二个目标是确定，使用 特异性受体拮抗剂，内源性血管紧张素II 影响清醒绵羊的压力感受器反射活动，以及这些 在怀孕期间，动作会被修改。最后，为了努力 理解为什么血浆肾素活性会随着怀孕而增加， 将确定之间的关系是否发生变化 出现肾灌注压和肾素分泌。压力感受性反射 将评估和比较孕妇和女性的功能 非孕清醒绵羊检视亲缘关系 血压与以下各项之间的关系 变量：加压素、肾素、皮质醇和促肾上腺皮质激素水平、心脏 心率、心输出量和外周阻力。血液中的变化 压力将产生30分钟的输液三剂 血管扩张剂硝普钠，或血容量改变 由出血引起的。探讨肾功能不全与肾功能的关系 灌流压力和肾素释放绵羊将被测量 使用肾动脉导管、封堵器和电磁装置 血流探头和肾静脉导管。肾动脉压 将以5-10毫米汞的步长减少15分钟，每次 取股动脉和肾静脉血检测肾素 将获得测量结果。肾动脉相关曲线 将为怀孕的绵羊构建肾素分泌压力 和未怀孕的绵羊确定肾脏压力感受器控制 肾素的释放会因怀孕而改变。

During pregnancy, blood volume increases by 30-40%, although the mechanism(s) by which the increase is maintained is unknown. In normal nonpregnant adults, the baroreceptor reflex plays a very important role in blood volume regulation. In this system increases in blood pressure and blood volume (sensed by stretch receptors located in the heart, carotid sinus, aortic arch kidney) inhibit the production of the volume retaining hormones vasopressin, ACTH and angiotensin II (via renin). Because the increased blood volume of pregnancy appears to be homeostatically maintained, this proposal seeks to test the hypothesis that baroreceptor reflex control of these hormones and other cardiovascular parameters is altered in the pregnant state to maintain the excess volume. In addition, angiotensin II has been shown to participate in baroreflex regulation of blood pressure, heart rate, cardiac output and vasopressin and ACTH secretion. A second aim of this proposal is to determine, using specific receptor antagonists, whether endogenous angiotensin II affects baroreflex activity in conscious sheep and whether these actions are modified during pregnancy. Finally, in a effort to understand why plasma renin activity is increased with gestation, it will be determined whether changes in the relationship between renal perfusion pressure and renin secretion occur. Baroreflex function will be assessed and compared in pregnant and nonpregnant conscious sheep by examining the relationship between blood pressure and each of the following variables: vasopressin, renin, cortisol and ACTH levels, heart rate, cardiac output and peripheral resistance. Changes in blood pressure will be produced with 30 min infusions of three doses of the vasodilator nitroprusside, or with changes in blood volume caused by hemorrhage. To study the relationship between renal perfusion pressure and renin release sheep will be instrumented with a renal arterial catheter, and occluder and electromagnetic flow probe and a renal venous catheter. Renal arterial pressure will be decreased in 5-10 mm Hg steps for 15 min at which time femoral arterial and renal venous blood samples for renin measurements will be obtained. Curves relating renal arterial pressure to renin secretion will be constructed for pregnant sheep and nonpregnant sheep to determine if renal baroreceptor control of renin release is altered by gestation.