VASOPRESSIN, ACTH AND RENIN SECRETION DURING PREGNANCY

在怀孕期间，血容量增加30- 40%， 维持增加的机制尚不清楚。 在正常的未怀孕的成年人中，压力感受器反射起着非常重要的作用。 在血容量调节中的重要作用。 在该系统中 血压和血容量增加（通过拉伸感测 受体位于心脏、颈动脉窦、主动脉弓肾） 抑制保容激素的产生 血管加压素、ACTH和血管紧张素II（通过肾素）。 因为 妊娠期血容量增加似乎是 保持体内平衡，这项建议旨在测试 假设压力感受器反射控制这些激素， 其他心血管参数在妊娠状态下改变 以保持多余的体积。 此外，血管紧张素II具有 被证明参与血液的压力反射调节 血压、心率、心输出量、加压素和ACTH 分泌物 本建议的第二个目的是确定，使用 特异性受体拮抗剂，无论是内源性血管紧张素II 影响清醒绵羊的压力反射活动， 在怀孕期间进行修改。 最后，为了 了解为什么血浆肾素活性随着妊娠而增加， 它将确定是否改变之间的关系， 发生肾灌注压和肾素分泌。 压力反射 将评估并比较妊娠和 非妊娠的有意识的绵羊，通过检查 血压与以下各项之间的关系 变量：血管加压素、肾素、皮质醇和ACTH水平，心脏 心率、心输出量和外周阻力。 血液变化 将在30分钟内输注三剂 血管扩张剂硝普钠，或与血容量的变化 出血引起的。 目的：探讨肾功能与糖尿病的关系。 灌注压和肾素释放绵羊将被仪器化 用肾动脉导管、封堵器和电磁 流量探针和肾静脉导管。 肾动脉压 将以5-10 mm Hg的步长降低15 min，此时 股动脉和肾静脉血样本用于测定肾素 将获得测量。 肾动脉相关曲线 对妊娠绵羊的肾素分泌产生压力 和非妊娠绵羊，以确定是否肾压力感受器控制 妊娠会改变肾素的释放

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.