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      The Influence of Concurrently Administered Theophylline, Ouabain and Hypocapnia on Coronary Flow Perturbations in the Perfused Guinea Pig Heart

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          Abstract

          Adenosine, potassium ions and hydrogen ions are known to be vasoactive in the coronary circulation. Little is known, however, about the combined effects of these chemicals during reactive hyperemia, flow autoregulation or hypoxic hyperemia. Isolated, perfused guinea pig hearts were used to study the influence of simultaneously administered theophylline, ouabain and alkalosis on coronary flow responses (occlusive hyperemia, autoregulation, hypoxic hyperemia) thought to be contributed to by the above chemicals. Retrograde aortic inflow was monitored electromagnetically in the absence and presence of concurrently administered theophylline (5 × 10<sup>–5</sup> M), ouabain (1.4 X 10<sup>–7</sup> M), and alkalosis (perfusate pH 7.69). Upon release of a 30-sec inflow occlusion (in the presence of the above agents) mean peak coronary flow was modestly, but significantly, reduced. Volume flow rate and time for flow to return 50% towards control were reduced in the presence of the above agents, but failed to return to pre-experimental values upon removal of blockers. When perfusion pressure was increased from 65 to 95 cm H<sub>2</sub>O (antagonists present), coronary myogenic autoregulation was significantly enhanced. Upon decreasing pressure from 95 to 35 cm H<sub>2</sub>O, in the presence of blockers, calculated coronary resistance fell from 13 ± 0.6 to 9.5 ± 0.5 cm H<sub>2</sub>O/ml/min. The latter value was significantly higher than that seen in the absence of test agents. No difference in the maximum mean coronary flow achieved by hypoxia (20% O<sub>2</sub>–5% Co<sub>2</sub>-balance N<sub>2</sub>) was seen in the absence or presence of blockers. In conclusion, these experiments provide some indirect support for the involvement of the above metabolites in reactive hyperemia and as antagonists of myogenic blood flow autoregulation. Little evidence for their involvement in hypoxic hyperemia is available from this study.

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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
          1981
          1981
          19 September 2008
          : 18
          : 1-2
          : 1-8
          Affiliations
          Department of Physiology, Giltner Hall, Michigan State University, East Lansing, Mich., and Department of Physiology, Cook College, Rutgers University, New Brunswick, N.J.
          Article
          158332 Blood Vessels 1981;18:1–8
          10.1159/000158332
          © 1981 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: 8
          Categories
          Research Paper

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