Preferential Myosin Heavy Chain Isoform B Expression May Contribute to the Faster Velocity of Contraction in Veins versus Arteries

Abstract

Smooth muscle myosin heavy chains occur in 2 isoforms, SMA (slow) and SMB (fast). We hypothesized that the SMB isoform is predominant in the faster-contracting rat vena cava compared to thoracic aorta. We compared the time to half maximal contraction in response to a maximal concentration of endothelin-1 (ET-1; 100 n M), potassium chloride (KCl; 100 m M) and norepinephrine (NE; 10 µ M). The time to half maximal contraction was shorter in the vena cava compared to aorta (aorta: ET-1 = 235.8 ± 13.8 s, KCl = 140.0 ± 33.3 s, NE = 19.8 ± 2.7 s; vena cava: ET-1 = 121.8 ± 15.6 s, KCl = 49.5 ± 6.7 s, NE = 9.0 ± 3.3 s). Reverse-transcription polymerase chain reaction supported the greater expression of SMB in the vena cava compared to aorta. SMB was expressed to a greater extent than SMA in the vessel wall of the vena cava. Western analysis determined that expression of SMB, relative to total smooth muscle myosin heavy chains, was 12.5 ± 4.9-fold higher in the vena cava compared to aorta, while SMA was 4.9 ± 1.2-fold higher in the aorta than vena cava. Thus, the SMB isoform is the predominant form expressed in rat veins, providing one possible mechanism for the faster response of veins to vasoconstrictors.

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: 2007

Publication date (Print): June 2007

Publication date (Electronic): 21 March 2007

Volume: 44

Issue: 4

Pages: 264-272

Affiliations

Departments of ^aPharmacology and Toxicology and ^bMedicine, Michigan State University, East Lansing, Mich., ^cDepartment of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vt., and ^dDepartment of Biological Sciences, Marquette University, Milwaukee, Wisc., USA

Article

Publisher ID: 100991 Other ID: J Vasc Res 2007;44:264–272

DOI: 10.1159/000100991

PubMed ID: 17377397

Copyright statement: © 2007 S. Karger AG, Basel

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.

Page count

Figures: 5, References: 33, Pages: 9

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Categories

Subject: Research Paper