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      Multiple Types of Chloride Channels in Bovine Pulmonary Artery Endothelial Cells

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          Abstract

          We have characterized two different types of Cl<sup>–</sup> currents in calf pulmonary artery endothelial (CPAE) cells by using a combined patch-clamp and Fura-2 microfluorescence technique to measure simultaneously ionic currents and the intracellular Ca<sup>2+</sup> concentration, [Ca<sup>2+</sup>]<sub>i</sub>. Exposure of CPAE cells to 28% hypotonic solution induces cell swelling without a change in membrane capacitance and [Ca<sup>2+</sup>]<sub>i</sub>, and concomitantly activates a current. This current, I<sub>Cl</sub>, <sub>vol</sub>, is closely correlated with the changes in cell volume and shows a modest outward rectification. It slowly inactivates at potentials more positive than +60 mV but is time- and voltage-independent at other potentials. Increase in [Ca<sup>2+</sup>]<sub>i</sub> by different maneuvers, such as application of vasoactive agonists (ATP), ionomycin, or loading of the cells directly with Ca<sup>2+</sup> also activates a Cl<sup>–</sup> current, I<sub>cl</sub><sub>ca</sub>· This current slowly activates at positive potentials, inactivates quickly at negative potentials and shows strong outward rectification. A time-independent component of the current activated by elevation of [Ca<sup>2+</sup>]<sub>i</sub> alone can be inhibited by cell shrinking by exposing the cells to hypertonic solution, indicating that an increase in [Ca<sup>2+</sup>]<sub>i</sub> also co-activates I<sub>Clvol</sub>· Forskolin or cAMP never activated a current in CPAE cells, which indicates the lack of cAMP-activated channels in these cells. There is also no evidence for the existence of voltage-gated C<sup>-</sup> channels in resting, nonstimulated cells. Challenging a cell with elevated [Ca<sup>2+</sup>]<sub>i</sub> and hypotonic solutions activated I<sub>Clvol</sub> on top of I<sub>Cl</sub><sub>ca</sub>, suggesting that I<sub>Cl Ca</sub> and I<sub>Clvol</sub> are different channels. We conclude that CPAE cells do not express voltage-gated (CIC-type) or cAMP-gated (CFTR-type) Cl<sup>-</sup> channels, but activate large Cl<sup>-</sup> currents after volume (mechanical?) or chemical (Ca<sup>2+</sup>) stimulation.

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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
          1997
          1997
          24 September 2008
          : 34
          : 3
          : 220-228
          Affiliations
          KU Leuven, Laboratorium voor Fysiologie, Campus Gasthuisberg, Leuven, Belgium
          Article
          159226 J Vasc Res 1997;34:220–228
          10.1159/000159226
          9226304
          © 1997 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.

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          Pages: 9
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