| Angiotensin-converting enzyme inhibition, but not AT(1) receptor blockade, in the solitary tract nucleus improves baroreflex sensitivity in anesthetized transgenic hypertensive (mRen2)27 rats. | |
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MedLine Citation:
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PMID: 21937997 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Transgenic hypertensive (mRen2)27 rats overexpress the murine Ren2 gene and have impaired baroreflex sensitivity (BRS) for control of the heart rate. Removal of endogenous angiotensin (Ang)-(1-7) tone using a receptor blocker does not further lower BRS. Therefore, we assessed whether blockade of Ang II with a receptor antagonist or combined reduction in Ang II and restoration of endogenous Ang-(1-7) levels with Ang-converting enzyme (ACE) inhibition will improve BRS in these animals. Bilateral solitary tract nucleus (nTS) microinjections of the AT(1) receptor blocker, candesartan (CAN, 24 pmol in 120 nl, n=9), or a peptidic ACE inhibitor, bradykinin (BK) potentiating nonapeptide (Pyr-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro; BPP9α, 9 nmol in 60 nl, n=12), in anesthetized male (mRen2)27 rats (15-25 weeks of age) show that AT(1) receptor blockade had no significant effect on BRS, whereas microinjection of BPP9α improved BRS over 60-120 min. To determine whether Ang-(1-7) or BK contribute to the increase in BRS, separate experiments using the Ang-(1-7) receptor antagonist D-Ala(7)-Ang-(1-7) or the BK antagonist HOE-140 showed that only the Ang-(1-7) receptor blocker completely reversed the BRS improvement. Thus, acute AT(1) blockade is unable to reverse the effects of long-term Ang II overexpression on BRS, whereas ACE inhibition restores BRS over this same time frame. As the BPP9α potentiation of BK actions is a rapid phenomenon, the likely mechanism for the observed delayed increase in BRS is through ACE inhibition and elevation of endogenous Ang-(1-7).Hypertension Research advance online publication, 22 September 2011; doi:10.1038/hr.2011.110. |
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Authors:
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Katsunori Isa; Amy C Arnold; Brian M Westwood; Mark C Chappell; Debra I Diz |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-9-22 |
Journal Detail:
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Title: Hypertension research : official journal of the Japanese Society of Hypertension Volume: - ISSN: 1348-4214 ISO Abbreviation: - Publication Date: 2011 Sep |
Date Detail:
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Created Date: 2011-9-22 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9307690 Medline TA: Hypertens Res Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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