Differentiation of Calcium Activation Mechanisms in Vascular Smooth Muscle by Selective Suppression with Verapamil and D 600

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Abstract

Mechanical activity of the isolated portal vein and thoracic aorta of the guinea-pig was recorded and the effects of verapamil and D 600 (methoxy-verapamü) on the dose-response curves to noradrenaline were measured. Extracellular electrical activity in portal vein was also sometimes recorded. Two calcium activation mechanisms could be differentiated: a ‘spike activation mechanism’ (SAM) inhibited by verapamil and D 600, and a ‘spike-free activation mechanism’ (SFAM) resistant to these antagonists in their specific concentration range (up to 10<sup>–5</sup> mol/l). In portal vein, both mechanisms were similarly dependent on extracellular calcium, indicating a D 600-resistant system for transmembrane calcium fluxes. The response of portal vein to increased potassium concentration was also tested. Species differences and differences in the specificity of various calcium antagonistic drugs complicate the picture of calcium antagonism in vascular smooth muscle.

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Author and article information

Journal

Journal ID (publisher-id): JVR

Journal ID (nlm-ta): J Vasc Res

Journal ID (doi): 10.1159/issn.1018-1172

Title: Journal of Vascular Research

Publisher: S. Karger AG

ISSN (Print): 1018-1172

ISSN (Electronic): 1423-0135

Publication date Subscription-year: 1975

Publication date (Print): 1975

Publication date (Electronic): 18 September 2008

Volume: 12

Issue: 1

Pages: 21-37

Affiliations

Department of Physiology, University of Marburg/Lahn, Marburg/Lahn

Article

Publisher ID: 158036 Other ID: Blood Vessels 1975;12:21–37

DOI: 10.1159/000158036

SO-VID: 510f4d0a-6461-4229-87e8-6c69783ba437

License:

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.

History

Date received : 22 July 1974

Page count

Pages: 17

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