ANGIOTENSIN II, VASOPRESSIN AND THE BARORECEPTOR REFLEX

静脉输注血管紧张素II（AII）改变压力感受性反射 使得心率和血管加压素和ACTH的血浆浓度 在每个动脉血压水平上都高于正常水平。 到 确定AII是否会增加这些激素和心率的水平 通过降低来自动脉和低血压的输入的紧张性抑制作用， 压力牵张感受器，感受器去神经对压力牵张感受器的影响， 将研究血管加压素、ACTH和对AII的心脏反应。 的作用 将通过确定 脊椎内注入AII或最后区病变对 压力感受器反射的功能。 将评估压力反射功能 通过研究血压和三种疾病之间的关系， 参数：心率和血管加压素的全身浓度， 促肾上腺皮质激素 血压将通过输注硝普钠 和苯乙醯胺或通过出血。 加压素输注似乎也影响压力反射功能， 增强反射的强度。 以确定该地区是否 postrema介导了这一作用，加压素输注对 压力感受性反射对该结构损伤犬ACTH分泌的控制 将被研究。 加压素输注是否能增强 还将研究ACTH分泌。 最后，内生性的作用 AII和加压素对压力感受性反射的调节作用 通过输注阻滞剂检查出血和缺水情况 或血管加压素拮抗剂。

Intravenous infusion of angiotensin II (AII) alters the baroreceptor reflex such that heart rate and plasma concentrations of vasopressin and ACTH are elevated above normal at each level of arterial blood pressure. To determine whether AII increases the levels of these hormones and heart rate by decreasing the tonic inhibitory effect of input from arterial and low pressure stretch receptors, the effect of abroreceptor denervation on the vasopressin, ACTH and cardiac response to AII will be studied. The role of the area postrema in the responses will be investigated by determining the effect of intravertebral infusion of AII or lesions of the area postrema on function of the baroreceptor reflex. Baroreflex function will be assessed by examining the relationship between blood pressure and each of three parameters: heart rate and systemic concentrations of vasopressin and ACTH. Blood pressure will be varied either by infusion of nitroprusside and phenylephrine, or by hemorrhage. Vasopressin infusion also appears to affect baroreflex function by enhancing the strength of the reflex. To determine whether the area postrema mediates this action, the effect of vasopressin infusion on baroreflex control of ACTH secretion in dogs with lesions of this structure will be studied. Whether vasopressin infusion enhances reflex release of ACTH secretion will also be investigated. Finally, the role of endogenous AII and vasopressin in regulation of the baroreceptor reflex during hemorrhage and water deprivation will be examined by infusion of blockers of the renin-angiotensin system or a vasopressin antagonist.