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      Angiotensin Induction of Active Responses in Cultured Reaggregates of Rat Aortic Smooth Muscle Cells

      ,

      Journal of Vascular Research

      S. Karger AG

      Vascular smooth muscle, Angiotensin, Cell culture, Electrical activity, Sodium, Calcium

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          Abstract

          Electrical activity was studied in cultured reaggregates of vascular smooth muscle cells prepared from the aortas of normotensive (WKY) and spontaneously hypertensive (SHR) rats. There were no significant differences between the resting membrane potentials of WKY (–44.7 ± 0.5 mV) and SHR (–45.6 ± 0.5 mV) reaggregates. Electrical field stimulation elicited active responses that consisted of two components: an initial spike component (amplitude, 30–40 mV; +V<sub>max</sub> 1–3 V/s) and a plateau component (amplitude, 10–30 mV; duration 3–5 s; +V<sub>max</sub>, 0.1–0.3 V/s). Often the spike component was absent. Both components of the response were abolished by verapamil, Mn<sup>++</sup>, and Na<sup>+</sup>-free solutions indicating that Na<sup>+</sup> and Ca<sup>++</sup> currents may be associated with them. Addition of 10 m M TEA increased the duration of the response, and addition of 0.5 m M BaCl<sub>2</sub> to the TEA solution increased the duration even further. The spike component always occurred in the presence of TEA and Ba<sup>++</sup>. No differences were observed between responses in WKY and SHR reaggregates. A bolus of angiotensin II (All) (bolus concentration of 1 µM) elicited a transient depolarization. In some cells an active membrane response was triggered by the depolarization and sometimes included the spike component. Replacing all the Na<sup>+</sup> in the solution with either Tris or choline resulted in loss of the response to All, and in some cells a hyperpolarization was actually seen on addition of the AH. The response to All was insensitive to verapamil (up to 10<sup>–5</sup> M), but was blocked by 1 m M MnCl<sub>2</sub>. Reaggregates from both WKY and SHR animals gave similar responses to AIL The data indicates that cultured reaggregates of vascular smooth muscle are electrically excitable and are sensitive to angiotensin. Therefore functional angiotensin receptors must be present in the cultured cells.

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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
          : 6
          : 263-279
          Affiliations
          Department of Physiology, University of Virginia School of Medicine, Charlottesville, Va., USA
          Article
          158360 Blood Vessels 1981;18:263–279
          10.1159/000158360
          © 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: 17
          Categories
          Research Paper

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