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      Differences in the Response of Three Embryologically Distinct Segments of the Isolated Canine Posterior Vena cava to Vasoactive Substances

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          Abstract

          The canine posterior vena cava was excised and divided into three embryologically distinct segments: segment A (supradiaphragm), segment B-C (intra-hepatic and that between liver and renal veins), and segment D (infrarenal). Circular and longitudinal strips were cut from each segment, suspended in Krebs bicarbonate solution and isometric tensions were recorded. The responses to six vasoactive agents, as well as transmural neural stimulation were studied. Maximum tension and ED<sub>50</sub> were obtained for norepinephrine, epinephrine, acetylcholine, bradykinin, histamine and 5-hydroxytryptamine (5-HT). The responses were not only quantitatively, but qualitatively different among the three segments. Bradykinin constricted the strip:; in A and B-C but not in D. 5-HT (<10<sup>–5</sup> m) caused a dose-dependent contraction in A and D through its direct stimulating action, while in C, a contractile response appeared only after administration of a higher dose of 5-HT. This was due to an indirect sympathomimetic action of the agent. Segment B-C, which histologically contained massive longitudinal muscle bundles in the outer layer of the wall, exhibited spontaneous, rhythmic contractions. The existence of a cholinergic excitatory innervation, in addition to adrenergic, was demonstrated in C by transmural neural stimulation.

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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
          978-3-8055-2857-3
          978-3-318-02028-1
          1018-1172
          1423-0135
          1978
          1978
          18 September 2008
          : 15
          : 1-3
          : 157-169
          Affiliations
          Department of Pharmacology, Nagoya University School of Medicine, Showa-Xu, Nagoya
          Article
          158161 Blood Vessels 1978;15:157–169
          10.1159/000158161
          © 1978 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: 13
          Categories
          Molecular and Cellular Aspects of Vascular Smooth Muscle in Health and Disease

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