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      Bioassay of an Endothelium-Derived Hyperpolarizing Factor from Bovine Coronary Arteries: Role of a Cytochrome P 450 Metabolite

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          Abstract

          An endothelium-derived hyperpolarizing factor (EDHF) mediates a part of the vasodilatory action of bradykinin. A bioassay method was developed to investigate the properties of EDHF on bovine coronary arterial smooth muscle cells. Cannulated bovine coronary arteries with an intact endothelium that were treated with indomethacin and N<sup>G</sup>-nitro- L-arginine methyl ester served as the EDHF donor. The effect of the donor vessel perfusate was examined on a 240 pS single-channel calcium (Ca<sup>2+</sup>)-activated potassium (K<sup>+</sup>) current (K<sub>Ca</sub>) and resting membrane potential in recipient coronary arterial smooth muscle cells. The open state probability (NPo) of the channel averaged 0.011 ± 0.003 during basal perfusate flow. After stimulation of the donor vessels with bradykinin (10<sup>–10</sup>–10<sup>–6</sup> M), the perfusate induced a 1.2- to 5-fold increase in the NPo (n = 7, p < 0.001). This increase in channel activity was attenuated by either removing the endothelium of the donor arterial segment or upon inhibition of cytochrome P<sub>450</sub> in the donor arterial segment with the combination of 17-octadecynoic acid and miconazole. The resting cell membrane averaged –60 ± 2 mV, and hyperpolarized to –69 ± 1.5 mV (n = 6, p < 0.05) in response to the perfusate following stimulation of the donor vessel with bradykinin. Addition of 14,15-epoxyeicosatrienoic acid mimicked the effects of the perfusate and increased the NPo of the K<sub>Ca</sub> channel from 0.01 ± 0.001 to 0.05 ± 0.001. These findings suggest that bradykinin stimulates the release of a transferable endothelial factor that activates K<sub>Ca</sub> channels and hyperpolarizes coronary arterial smooth muscle cell membranes. These findings support the hypothesis that coronary arteries release an EDHF which is a cytochrome P<sub>450</sub> metabolite of arachidonic acid.

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          Endothelium-dependent hyperpolarization: a role in the control of vascular tone

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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
            1998
            August 1998
            07 August 1998
            : 35
            : 4
            : 274-284
            Affiliations
            Departments of Physiology, Pharmacology & Toxicology and The Cardiovascular Research Center, Medical College of Wisconsin, and The Clement Zablocki Medical Center, Milwaukee, Wisc., USA
            Article
            25594 J Vasc Res 1998;35:274–284
            10.1159/000025594
            9701712
            © 1998 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: 11
            Categories
            Research Paper

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