Uptake and O-Methylation of Isoprenaline in the Rabbit Ear Artery

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Abstract

Factors which influence uptake and O-methylation of 3Hisoprenaline (3HISO) by isolated segments of the rabbit ear artery were investigated. The tendency of the artery to accumulate unchanged amine was enhanced either when the O-methylation of ISO approached saturation at a high substrate concentration (6 µmol l–1 ISO), or when O-methylation was inhibited. Under these conditions, deoxycorticosterone acetate (DOCA) partially inhibited the accumulation of ISO. DOCA exerted a stronger inhibitory effect on O-methylation, but only at low ISO concentrations (0.2 and 0.8 µmol l–1). The results are interpreted as evidence that (a) O-methylation in the intact artery is a saturable process which serves to limit the accumulation of 3HISO when the bathing concentration of the amine is low, and (b) DOCA exerts its effects by inhibiting extraneuronal uptake into the compartment possessing O-methylating activity. Analysis of the kinetics of efflux of 3HISO suggested that O-methylation was restricted to only one compartment, whereas unchanged ISO was accumulated within at least two compartments in addition to the extracellular compartment. Attention is drawn to a small but significant inhibitory effect of chronic sympathetic denervation on the accumulation, although not the O-methylation of ISO, raising the possibility that there may also be distribution of 3HISO within the sympathetic nerves.

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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: 1980

Publication date (Print): 1980

Publication date (Electronic): 19 September 2008

Volume: 17

Issue: 5

Pages: 229-245

Affiliations

Department of Human Physiology and Pharmacology, University of Adelaide, Adelaide, S.A.

Article

Publisher ID: 158253 Other ID: Blood Vessels 1980;17:229–245

DOI: 10.1159/000158253

SO-VID: f9261e4a-8554-404c-937f-3694e628241d

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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 : 31 January 1978

Date accepted : 07 January 1980

Page count

Pages: 17

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