Chronic treatment with enalapril and valsartan significantly improved endothelium-dependent relaxations of aortas from ovariectomized rats. The present results clearly point to that chronic treatment with enalapril or valsartan reduced expression and function of RAS and associated oxidative stress, thereby augmented NO bioavailability and improved endothelium-dependent relaxations. These results provided novel evidence supporting a potential application of ACEI and ARB in the treatment of endothelial dysfunction-associated vascular complications in postmenopausal women. / Functional studies showed that acetylcholine-induced relaxations in isolated aortas were impaired in a time-dependent manner, from the 4th-week to the 12th-week after ovariectomy. The impaired relaxations were partially restored by acute treatment with losartan [angiotensin II type 1 receptor (AT1R) blocker] and apocynin [NAD(P)H oxidase inhibitor]. The present results demonstrate that estrogen deficiency blunted endothelium-dependent relaxations due to impaired the NO bioavailability, which is closely associated with the reduced eNOS activity and elevated RAS expression and associated NAD(P)H oxidase-mediated oxidative stress in the vascular wall. / The present study shows that chronic consumption of cranberry juice restored the endothelium-dependent relaxations in aortas from ovariectomized rats. In ovariectomized rats, the phenylephrine-induced a higher active vascular tension; which was prevented by chronic consumption of cranberry juice. The present data also shows that cranberry juice administration significantly reduces the elevated serum levels of total cholesterol, triglyceride, high density lipoprotein (HDL) cholesterol, non-HDL (nHDL) cholesterol, and nHDL/HDL. The active ingredients in the cranberry juice organic extract accounting for the vascular benefit remain to be further examined even though the extract causes endothelial NO-dependent relaxations in normal rat aortas and contains several bioactive compounds, some of which may protect the vascular function. This study provides the first line of evidence concerning a significant vascular benefit of chronic consumption of cranberry juice during estrogen deficiency. (Abstract shortened by UMI.) / The present study used ovariectomized female rats that mimic the "equivalent" state of menopause in human and investigated whether dysregulation of RAS components contribute to endothelial dysfunction and whether chronic treatment with ACEI (enalapril) or ARB (valsartan) could restore endothelial function in ovariectomized rats. / The second objective of the present study was to investigate whether or not consumption of cranberry juice, a popular drink in Western countries, could restore endothelial function during estrogen deficiency and to elucidate the cellular mechanisms underlying the improved endothelial function. / Yung, Lai Ming. / Adviser: Huana Yu. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3252. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 148-168). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344207 |
| Date | January 2008 |
| Contributors | Yung, Lai Ming., Chinese University of Hong Kong Graduate School. Division of Physiology. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xxiii, 168 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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