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

      Margatoxin Inhibits VEGF-Induced Hyperpolarization, Proliferation and Nitric Oxide Production of Human Endothelial Cells

      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

          Background: Vascular endothelial growth factor (VEGF) induces proliferation of endothelial cells (EC) in vitro and angiogenesis in vivo. Furthermore, a role of VEGF in K<sup>+</sup> channel, nitric oxide (NO) and Ca<sup>2+</sup> signaling was reported. We examined whether the K<sup>+</sup> channel blocker margatoxin (MTX) influences VEGF-induced signaling in human EC. Methods: Fluorescence imaging was used to analyze changes in the membrane potential (DiBAC), intracellular Ca<sup>2+</sup> (FURA-2) and NO (DAF) levels in cultured human EC derived from human umbilical vein EC (HUVEC). Proliferation of HUVEC was examined by cell counts (CC) and [<sup>3</sup>H]-thymidine incorporation (TI). Results: VEGF (5–50 ng/ml) caused a dose-dependent hyperpolarization of EC, with a maximum at 30 ng/ml (n = 30, p < 0.05). This effect was completely blocked by MTX (5 µmol/l). VEGF caused an increase in transmembrane Ca<sup>2+</sup> influx (n = 30, p < 0.05) that was sensitive to MTX and the blocker of transmembrane Ca<sup>2+</sup> entry 2-aminoethoxydiphenyl borate (APB, 100 µmol/l). VEGF-induced NO production was significantly reduced by MTX, APB and a reduction in extracellular Ca<sup>2+</sup> (n = 30, p < 0.05). HUVEC proliferation, examined by CC and TI, was significantly increased by VEGF and inhibited by MTX (CC: –58%, TI –121%); APB (CC –99%, TI –187%); N-monomethyl- L-arginine (300 µmol/l: CC: –86%, TI –164%). Conclusions: VEGF caused an MTX-sensitive hyperpolarization which results in an increased transmembrane Ca<sup>2+</sup> entry that is responsible for the effects on endothelial proliferation and NO production.

          Related collections

          Most cited references 17

          • Record: found
          • Abstract: not found
          • Article: not found

          Tumor cells secrete a vascular permeability factor that promotes accumulation of ascites fluid

           D Senger,  S Galli,  A. Dvorak (1983)
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Nitric oxide production contributes to the angiogenic properties of vascular endothelial growth factor in human endothelial cells.

            Vascular endothelial growth factor (VEGF) is a regulator of vasculogenesis and angiogenesis. To investigate the role of nitric oxide (NO) in VEGF-induced proliferation and in vitro angiogenesis, human umbilical vein endothelial cells (HUVEC) were used. VEGF stimulated the growth of HUVEC in an NO-dependent manner. In addition, VEGF promoted the NO-dependent formation of network-like structures in HUVEC cultured in three dimensional (3D) collagen gels. Exposure of cells to VEGF led to a concentration-dependent increase in cGMP levels, an indicator of NO production, that was inhibited by nitro-L-arginine methyl ester. VEGF-stimulated NO production required activation of tyrosine kinases and increases in intracellular calcium, since tyrosine kinase inhibitors and calcium chelators attenuated VEGF-induced NO release. Moreover, two chemically distinct phosphoinositide 3 kinase (PI-3K) inhibitors attenuated NO release after VEGF stimulation. In addition, HUVEC incubated with VEGF for 24 h showed an increase in the amount of endothelial NO synthase (eNOS) protein and the release of NO. In summary, both short- and long-term exposure of human EC to VEGF stimulates the release of biologically active NO. While long-term exposure increases eNOS protein levels, short-term stimulation with VEGF promotes NO release through mechanisms involving tyrosine and PI-3K kinases, suggesting that NO mediates aspects of VEGF signaling required for EC proliferation and organization in vitro.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Identification of the KDR tyrosine kinase as a receptor for vascular endothelial cell growth factor.

              Vascular endothelial cell growth factor (VEGF), also known as vascular permeability factor, is an endothelial cell mitogen which stimulates angiogenesis. Here we report that a previously identified receptor tyrosine kinase gene, KDR, encodes a receptor for VEGF. Expression of KDR in CMT-3 (cells which do not contain receptors for VEGF) allows for saturable 125I-VEGF binding with high affinity (KD = 75 pM). Affinity cross-linking of 125I-VEGF to KDR-transfected CMT-3 cells results in specific labeling of two proteins of M(r) = 195 and 235 kDa. The KDR receptor tyrosine kinase shares structural similarities with a recently reported receptor for VEGF, flt, in a manner reminiscent of the similarities between the alpha and beta forms of the PDGF receptors.
                Bookmark

                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
                2005
                October 2005
                28 September 2005
                : 42
                : 5
                : 368-376
                Affiliations
                Departments of aCardiology and Angiology, and bPhysiology, Justus Liebig University of Giessen, Giessen, Germany
                Article
                87159 J Vasc Res 2005;42:368–376
                10.1159/000087159
                16043967
                © 2005 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: 4, References: 38, Pages: 9
                Categories
                Research Paper

                Comments

                Comment on this article