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      Effects of 2-[(5-Chloro-2-methoxyphenyl)azo]-1H-imidazole (M6434), a New α-Adrenoceptor Agonist, on Pre- and Postsynaptic α-Adrenoceptors in Canine Mesenteric Artery

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          Abstract

          Post- and presynaptic α-adrenoceptors in the canine mesenteric artery show distinct features of α<sub>1</sub> and α<sub>2</sub> types, respectively. The effects of a newly synthesized pressor agent, 2-[(5-chloro-2-methoxyphenyl)azo]-1H-imidazole (M6434), on the pre- and postsynaptic α-adrenoceptors of the canine mesenteric artery were examined pharmacologically. M6434 produced a contractile response in the mesenteric artery. The EC<sub>5</sub>o value of M6434 was 1.1 × 10<sup>–7</sup> M, that was almost the same as that of norepinephrine but significantly lower than the value seen with methoxamine. The maximum amplitude of contraction developed by M6434 was approximately 81 % of that induced by norepinephrine. The contractile response to M6434 was competitively inhibited by prazosin (pA<sub>2</sub> = 9.23 ± 0.08) and yohimbine (pA<sub>2</sub> = 7.85 ± 0.09). M6434 also reduced the <sup>3</sup>H-efflux evoked by electrical transmural stimulation in the arterial tissues preincubated with <sup>3</sup>H-norepinephrine, and the maximum inhibition corresponded to about 60 % of the case of norepinephrine. This presynaptic effect was inhibited by yohimbine but not by prazosin. The results show that M6434 is almost a full agonist for α<sub>1</sub>-adrenoceptor with partial α<sub>2</sub>-effect.

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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
          1984
          1984
          23 September 2008
          : 21
          : 5
          : 246-251
          Affiliations
          Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
          Article
          158517 Blood Vessels 1984;21:246–251
          10.1159/000158517
          © 1984 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: 6
          Categories
          Research Paper

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