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      Modification by Temperature of the Response of Isolated Aorta to Stimulatory Agents and Transmural Stimulation

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          Abstract

          Contractile responses of helically-cut strips of the rabbit aorta to drugs, ions and transmural electrical stimulation were compared at different temperatures of the bathing medium, the response at 37 °C being taken as control. The dose-response curve of norepinephrine was moved to the right and downward by lowering the temperature from 37 to 25 °C and by raising temperature to 40 °C. Responses to transmural neural stimulation at frequencies of 5 and 20/sec were attenuated at 25 °C, the attenuation being greater in the response at the lower frequency. Concentrations of exogenous norepinephrine needed to produce the same magnitude of contraction as that with transmural stimulation were markedly increased by lowering the temperature to 25 °C. Contractile responses to norepinephrine (2 x 10<sup>-6</sup> m), histamine (2 × 10<sup>-5</sup> m) and angiotensin II (10<sup>-7</sup> m) were attenuated by 32–44% at 25 °C, whereas the responses to K<sup>+</sup> (25 mil) and Ba<sup>++</sup> (2 mil) were dependent on temperatures between 25 and 37 °C and were attenuated by 69 and 92%, respectively, at 25 °C. Contractures induced by Ca<sup>++</sup> in K<sup>+</sup>-depolarized preparations exposed to Ca<sup>++</sup>-free media and also by Ba<sup>++</sup> in preparations exposed to Ca<sup>++</sup>-free media varied directly by raising temperatures. Interference with the influx of divalent cations, such as Ca<sup>++</sup> and Ba<sup>++</sup>, may be involved in the cold inhibition of aortic contractility.

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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
          1976
          1976
          18 September 2008
          : 13
          : 4
          : 210-221
          Affiliations
          Department of Pharmacology, Faculty of Medicine, Kyoto University, Kyoto
          Article
          158090 Blood Vessels 1976;13:210–221
          10.1159/000158090
          © 1976 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: 12
          Categories
          Research Paper

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