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      Mechanisms of Histamine-Induced Coronary Vasodilatation: H 1-Receptor-Mediated Release of Endothelium-Derived Nitric Oxide

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          Abstract

          Although the content of histamine in myocardial tissue is high, its contribution to the regulation of coronary blood flow has not been clearly defined. The aim of the present study was to investigate whether or not nitric oxide (NO), an important modulator of coronary vascular tone, is involved in histamine-induced coronary vasomotion and to characterize which histaminergic receptor subtype mediates this process. Isolated, constant-flow-perfused guinea pig hearts were challenged with histamine, the H<sub>1</sub>-receptor agonist pyridyleth-ylamine (PYR) and the H<sub>2</sub>-receptor agonist dimaprit (DIM). Apart from coronary perfusion pressure (CPP), left ventricular pressure (LVP) and the development of contractile force (dp/dt), the release of NO and cyclic GMP (cGMP) were continuously measured. Histamine and DIM induced concentration dependently a coronary vasodilatation with an almost 50% decrease in CPP paralleled by an enhancement of LVP and dp/dt by more than 80%. PYR selectively reduced CPP by 47% without affecting LVP and dp/dt. Histamine-and PYR-induced coronary vasodilatation were paralleled by a more-than-twofold increase in basal cGMP release from isolated hearts, whereas DIM exerted no effects on cGMP release. Oxyhemoglobin (4 µ M), an effective scavenger of NO, shifted the concentration-response curve for histamine- and PYR-induced changes in CPP significantly to the right and in parallel inhibited the increase in cGMP release. Histamine and PYR rapidly (within 2 s) decreased CPP, while the onset of DIM-induced coronary vasodilatation followed changes in LVP with a lag period of 10 s. Histamine increased basal NO release concentration dependently by a maximum of 351 ± 21 pmol/min. Amounts of NO released were within the vasodilatory effective range of exogenously applied NO. These data suggest that the rapid onset of histamine-induced coronary vasodilatation is mediated via the activation of H<sub>1</sub> receptors with the subsequent release of endothelium-derived NO followed by a long-lasting and profound component which is due to the H<sub>2</sub>-receptor-mediated increase in LVP. Amounts of NO released upon stimulation of endothelial H<sub>1</sub> receptors are sufficient to fully account for the increase in cGMP and the observed coronary vasodilatation.

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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
          1993
          1993
          23 September 2008
          : 30
          : 3
          : 132-138
          Affiliations
          aDepartment of Cardiology, Heinrich-Heine-University, Dusseldorf; bDepartment of Pharmacology, Schwarz Pharma AG, Monheim, FRG
          Article
          158987 J Vasc Res 1993;30:132–138
          10.1159/000158987
          8518330
          © 1993 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
          Pages: 7
          Categories
          Research Paper

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