A Pharmacological Analysis of the α-Adrenoceptor Antagonism by Prazosin in Arteries and Veins

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Abstract

The hemodynamic profile following administration of prazosin suggests that it may be a less effective antagonist of postsynaptic α-adrenoceptors in veins than in arteries. One possible explanation for this would be if there exist more than one postsynaptic α-adrenoceptor subtype and if these subtypes varied in their distribution between arteries and veins. We addressed this question by examining the extent of the antagonism by prazosin of norepinephrine-induced increases in vasomotor tone in several arteries and veins in vitro, including the thoracic aorta of the guinea pig and the portal vein, saphenous artery and vein, and the renal artery and vein of the rabbit. Dose-response curves were constructed following increasing concentrations of prazosin. Based on these dose-response curves, and analysis of the various dose ratios using the Schild plot, we conclude that prazosin displays the characteristics of an equilibrium competitive antagonist at postsynaptic α-adrenoceptors in arteries and veins in vitro, and that prazosin displays little, if any, selectivity for arteries in comparison to veins.

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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: 1982

Publication date (Print): 1982

Publication date (Electronic): 19 September 2008

Volume: 19

Issue: 2

Pages: 79-87

Affiliations

Department of Pharmacology and Toxicology, West Virginia University Medical Center, Morgantown, W.Va., USA

Article

Publisher ID: 158375 Other ID: Blood Vessels 1982;19:79–87

DOI: 10.1159/000158375

SO-VID: f1f93a02-3728-4a56-8d89-59c83972864e

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 : 01 May 1981

Date accepted : 11 July 1981

Page count

Pages: 9

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