Brooks V L, Keil L C
Department of Physiology, Oregon Health Sciences University, Portland 97201-3098.
Am J Physiol. 1992 Oct;263(4 Pt 2):R762-9. doi: 10.1152/ajpregu.1992.263.4.R762.
Angiotensin II (ANG II) and vasopressin participate in baroreflex regulation of adrenocorticotropic hormone (ACTH), glucocorticoid, and renin secretion. The purpose of this study was to determine whether this participation is enhanced in water-deprived dogs, with chronically elevated plasma ANG II and vasopressin levels, compared with water-replete dogs. The baroreflex was assessed by infusing increasing doses of nitroprusside (0.3, 0.6, 1.5, and 3.0 micrograms.kg-1.min-1) in both groups of animals. To quantitate the participation of ANG II and vasopressin, the dogs were untreated or pretreated with the competitive ANG II antagonist saralasin, a V1-vasopressin antagonist, or combined V1/V2-vasopressin antagonist, either alone or in combination. The findings were as follows. 1) Larger reflex increases in ANG II, vasopressin, and glucocorticoids, but not ACTH, were produced in water-deprived dogs compared with water-replete dogs. 2) ANG II blockade blunted the glucocorticoid and ACTH responses to hypotension in water-deprived dogs, but not water-replete dogs. In contrast, vasopressin blockade reduced the ACTH response only in water-replete dogs. 3) Vasopressin or combined vasopressin and ANG II blockade reduced the plasma level of glucocorticoids related either to the fall in arterial pressure or to the increase in plasma ACTH concentration in water-replete dogs, and this effect was enhanced in water-deprived dogs. 4) In both water-deprived and water-replete animals, saralasin and/or a V1-antagonist increased the renin response to hypotension, but a combined V1/V2-antagonist did not. These results reemphasize the importance of endogenous ANG II and vasopressin in the regulation of ACTH, glucocorticoid, and renin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
血管紧张素II（ANG II）和血管加压素参与促肾上腺皮质激素（ACTH）、糖皮质激素和肾素分泌的压力反射调节。本研究的目的是确定与水充足的犬相比，在长期血浆ANG II和血管加压素水平升高的缺水犬中，这种参与作用是否增强。通过向两组动物输注递增剂量的硝普钠（0.3、0.6、1.5和3.0微克·千克-1·分钟-1）来评估压力反射。为了量化ANG II和血管加压素的参与作用，对犬不进行处理或用竞争性ANG II拮抗剂沙拉新、V₁血管加压素拮抗剂或联合V₁/V₂血管加压素拮抗剂单独或联合进行预处理。结果如下：1）与水充足的犬相比，缺水犬中ANG II、血管加压素和糖皮质激素的反射性升高幅度更大，但ACTH没有。2）ANG II阻断减弱了缺水犬对低血压的糖皮质激素和ACTH反应，但对水充足犬没有。相反，血管加压素阻断仅降低了水充足犬的ACTH反应。3）血管加压素或血管加压素与ANG II联合阻断降低了水充足犬中与动脉压下降或血浆ACTH浓度升高相关的糖皮质激素血浆水平，且在缺水犬中这种作用增强。4）在缺水和水充足的动物中，沙拉新和/或V₁拮抗剂增加了对低血压的肾素反应，但联合V₁/V₂拮抗剂则没有。这些结果再次强调了内源性ANG II和血管加压素在ACTH、糖皮质激素和肾素分泌调节中的重要性。（摘要截短于250字）
