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

      Effects of Cl Substitution on Electrophysiological Properties, Ca 2+ Influx and Prolactin Secretion of Rat Lactotropes in vitro

      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

          In this study, we compared the effects of different chloride (Cl<sup>–</sup>) substitutes – methane sulfonate (CH<sub>3</sub>SO<sup>–</sup><sub>3</sub>), bromide (Br<sup>–</sup>), nitrate (NO<sup>–</sup><sub>3</sub>), thiocyanate (SCN<sup>–</sup>) and perchlorate (ClO<sup>–</sup><sub>4</sub>) – on the secretory activity and calcium current activation of rat lactotropes in primary culture. We observed that CH<sub>3</sub>SO<sup>–</sup><sub>3</sub> decreased basal prolactin (PRL) secretion. Br<sup>–</sup> had no effect, whereas the more lyotropic anions, such as NO<sup>–</sup><sub>3</sub>, SCN<sup>–</sup> and ClO<sup>–</sup><sub>4</sub>, increased basal PRL secretion. The latter three substitutes induced a significant shift in the voltage dependence of T-type calcium channel activation towards hyperpolarized values. However, this shift alone cannot explain the increase in secretion. Anion permeability studies also demonstrated that the organic anion CH<sub>3</sub>SO<sup>–</sup><sub>3</sub> was less permeant than Cl<sup>–</sup>, whereas monovalent inorganic anions were more permeant, with the following anion permeability sequence: SCN<sup>–</sup> > ClO<sup>–</sup><sub>4</sub> > NO<sup>–</sup><sub>3</sub> > Br<sup>–</sup>. In conclusion, deprivation of Cl<sup>–</sup> ions has converse consequences on basal and induced secretion; permeating anions result in a transient increase in intracellular Ca<sup>2+</sup> ions. This process involves voltage-dependent Ca<sup>2+</sup> channels. We propose that an alteration in intracellular anion concentrations may influence the activation of internal effectors such as G proteins or channel proteins and, therefore, interfere with exocytosis. These effects are correlated with an external action of lyotropic anions, particularly NO<sup>–</sup><sub>3</sub>, ClO<sup>–</sup><sub>4</sub> and SCN<sup>–</sup>, on the gating properties of T-type calcium channels, probably through changes in cell surface charges. The results demonstrate the modulatory effect of anions on the secretory activity of rat lactotropes and underline the specific role played by chloride in stimulus-secretion coupling.

          Related collections

          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1999
          November 1999
          17 November 1999
          : 70
          : 5
          : 332-342
          Affiliations
          aDepartamento de Ciencias Fisiologicas, Facultad de Salud, Universidad del Valle, Cali, Colombia; bCNRS UMR 5543, Université Victor-Segalen Bordeaux-2, Bordeaux, France
          Article
          54494 Neuroendocrinology 1999;70:332–342
          10.1159/000054494
          10567859
          © 1999 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
          Figures: 5, Tables: 2, References: 30, Pages: 11
          Categories
          Pituitary Transduction

          Comments

          Comment on this article