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      Effect of Temperature and Coronary Flow on the Metabolic and Mechanical Function of the Isolated Rat Heart

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          Abstract

          A number of cardiac metabolic intermediates, namely, adenosine triphosphate (ATP), H+, phosphocreatine (PCr), inorganic phosphate (Pi), adenosine diphosphate (ADP), and related functions of these intermediates, Gibbs’ free energy of ATP hydrolysis (ΔG) and phosphorylation ratio [ATP/(ADP·Pi)], are thought to adjust mitochondrial oxidative phosphorylation rates to conform to mechanical demand. The effects of hypothermia and altered perfusion pressure on these parameters were evaluated in 12 hearts from Sprague-Dawley rats perfused in the Langendorff mode. <sup>31</sup>P-nuclear magnetic resonance (NMR) spectra were obtained at cardiac temperatures between 20 and 37 °C, and coronary perfusion pressures between 20 and 145 cm H<sub>2</sub>O. Coronary flow varied between 0.5 and 15ml/min throughout this range of intervention. Heart rate (HR), left ventricular systolic pressure (LVSP), and specific volumetric coronary flow (SCF) were determined for each temperature and perfusion pressure. The product HR × LVSP directly correlated with perfusion pressure at all temperatures. The temperature dependence could be represented by an overall activation energy of 72.7 kJ/M. In the constant temperature experiment, SCF and HR × LVSP fell linearly with decreasing perfusion pressure. Quantitative evaluation of the relationship between cardiac function and the metabolic intermediates described above defined these intermediates as nonregulatory with the possible exception of H+.

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          Author and article information

          Journal
          CRD
          Cardiology
          10.1159/issn.0008-6312
          Cardiology
          S. Karger AG
          0008-6312
          1421-9751
          1993
          1993
          14 November 2008
          : 82
          : 4
          : 238-248
          Affiliations
          Departments of aBiochemistry and Biophysics and bMedicine (Cardiology), University of Pennsylvania School of Medicine, Philadelphia, Pa., USA
          Article
          175871 Cardiology 1993;82:238–248
          10.1159/000175871
          8402750
          © 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: 11
          Categories
          General Cardiology, Basic Research

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