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      Increased Coronary Vascular Resistance Cannot Be Reduced by Inhibiting Sympathetic Overactivity in Hypertension

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          Abstract

          The aim of this study was to test whether increased coronary vascular resistance in hypertensive subjects can be reduced by centrally inhibiting sympathetic overactivity with dexamethasone. Coronary vascular resistance was quantitated in 11 men with untreated mild essential hypertension (RR 149 ± 13/98 ± 10 mm Hg) and 23 healthy, normotensive, otherwise matched men using positron emission tomography and [<sup>15</sup>O]H<sub>2</sub>O. The measurements were performed at baseline and during adenosine stimulation. Each subject was studied twice, with and without previous dexamethasone treatment for two days (0.5 mg × 4 per day). Before dexamethasone treatment, cardiac index and plasma norepinephrine concentration (1.9 ± 0.6 vs. 1.3 ± 0.5 nmol/l, p < 0.01) were significantly higher in hypertensive than in normotensive subjects. Additionally, both baseline and hyperemic coronary vascular resistances were higher in hypertensive than normotensive subjects (147 ± 31 vs. 113 ± 24 and 36 ± 9 vs. 25 ± 10 mm Hg·min·g·ml<sup>–1</sup>; p < 0.05). Dexamethasone treatment significantly decreased plasma norepinephrine concentrations in hypertensive subjects, leading to comparable plasma norepinephrine concentrations in hypertensive and normotensive subjects (1.4 ± 0.5 vs. 1.2 ± 0.4 nmol/l; NS). However, coronary vascular resistances remained increased in hypertensive subjects. In conclusion, hypertensive subjects are characterized by sympathetic overactivity, which can be normalized by dexamethasone. However, coronary vascular resistances remained increased in hypertensive subjects after dexamethasone treatment, suggesting that other mechanisms than sympathetic overactivity-induced vasoconstriction explain the increased coronary vascular resistance in hypertension.

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          Author and article information

          Journal
          JVR
          J Vasc Res
          10.1159/issn.1018-1172
          Journal of Vascular Research
          S. Karger AG
          1018-1172
          1423-0135
          2002
          October 2002
          18 September 2002
          : 39
          : 5
          : 456-462
          Affiliations
          aTurku PET Centre, Departments of bMedicine and cClinical Physiology, Turku University, Turku, Finland
          Article
          64520 J Vasc Res 2002;39:456–462
          10.1159/000064520
          12297708
          © 2002 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Figures: 2, Tables: 2, References: 34, Pages: 7
          Categories
          Research Paper

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