Blog
About

0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      Memory of Previous Receptor Activation Induces a Delay in Ca 2+ Mobilization and Decreases the [Ca 2+] i Sensitivity of Arterial Contractions

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          α<sub>1</sub>-Adrenoceptor agonists not only contract rabbit femoral arteries, but also desensitize them so that the strength of subsequent contractions induced by 110 mM KCl is reduced. To determine the mechanisms by which this postreceptor desensitization occurs, tissues loaded with fura-2/AM were pretreated with phenylephrine (PE), washed, then activated with submaximum (23 mM) and maximum (30 mM) KCl concentrations. Pretreatment of tissues with 1 µMPE for 1–30 min resulted in reductions compared to control in the ability of 30 mM KCl to increase stress (force/tissue cross-sectional area). Pretreatment durations of 20 or 30 min with 10 µM PE also introduced delays between addition of KCl and commencement of both contraction (9.8 ± 0.8 and 2.4 ± 1.4 min when stimulated with, respectively, 23 and 30 mM KCl) and an increase in [Ca<sup>2+</sup>]i. At the end of the delay period, both [Ca<sup>2+</sup>]i and stress spontaneously increased, but although [Ca<sup>2+</sup>]i increased to control levels, stress did not. These data support the hypothesis that at least two postreceptor desensitizing mechanisms are activated by prior αi-adrenoceptor stimulation: (1) short-term inhibition of stimulus-induced increases in [Ca<sup>2+</sup>]i and (2) reductions in the sensitivity of the contractile response to [Ca<sup>2+</sup>]i. Interestingly, caffeine pretreatment mimicked the actions of PE pretreatment, implying that the superficial buffer barrier function of the sarcoplasmic reticulum or increases in cyclic nucleotide levels may have played a role in memory of α-adrenoceptor activation in rabbit femoral arteries.

          Related collections

          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
          1996
          1996
          24 September 2008
          : 33
          : 6
          : 489-498
          Affiliations
          Department of Pharmacology, Eastern Virginia Medical School, Norfolk, Va., USA
          Article
          159188 J Vasc Res 1996;33:489–498
          10.1159/000159188
          8998198
          © 1996 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: 10
          Categories
          Research Paper

          Comments

          Comment on this article