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      Modification of Ischemia/ Reperfusion-lnduced Ion Shifts (Na +, K +, Ca 2+ and Mg 2+) by Free Radical Scavengers in the Rat Retina


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          We investigated the contribution of scavenging of oxygen free radicals to retinal ion contents during ischemia and reperfusion with the use of super-oxide dismutase (SOD, Sigma), allopurinol (Sigma), EGB 761 (extract of Ginkgo biloba, Tanakan, IPSEN, Paris, France) and allopurinol plus EGB 761 in the rat. SOD (15,000 U/kg/day), allopurinol (50 mg/kg/day), EGB 761 (100 mg/kg/day) and allopurinol (50 mg/kg/day) plus EGB 761 (100 mg/kg/day) were administered for 10 days, respectively. Then, the eyes were subjected to 90 min of ischemia followed by 4 and 24 h of reperfusion, respectively. Retinal Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup> and Mg<sup>2+</sup> contents were measured by atomic absorption spectrophotometry after the washing out of blood and extracellular fluid from the vasculature. SOD, EGB 761 and the combination of EGB 761 with allopurinol significantly reduced the ischemia/reperfusion-induced Na<sup>+</sup> and Ca<sup>2+</sup> accumulation and K<sup>+</sup> loss in ischemic/reperfused retinal tissue. Allopurinol alone failed to reduce the maldistribution of Na<sup>+</sup>, Ca<sup>2+</sup> and K<sup>+</sup> induced by ischemia/reperfusion in the retina. Neither intervention inhibited the cell Mg<sup>2+</sup> loss which was observed during ischemia and reperfusion. Despite the responsible mechanisms remaining controversial, many studies confirmed that ischemia/reperfusion could trigger very sudden metabolic, electrophysiologic, morphologic and functional changes. There is general agreement that major ionic shifts are implicated; what triggers these changes is unclear, although many investigators believe that free radicals and oxidant stress may be important. In conclusion, our results show that direct scavenging activity of free radical scavengers reduce the maldistribution of ionic shifts induced by ischemia/reperfusion, while allopurinol, an inhibitor of the conversion of xanthine dehydrogenase to xanthine oxidase, does not attenuate reperfusion-induced ion shifts.

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          Author and article information

          Ophthalmic Res
          Ophthalmic Research
          S. Karger AG
          10 December 2009
          : 25
          : 1
          : 1-9
          aInstitut Henri Beaufour, Courtabæœuf; bIPSEN, Paris; cLaboratoire de Biophysique, Clermont-Ferrand, France
          267214 Ophthalmic Res 1993;25:1–9
          © 1993 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.

          : 23 September 1991
          : 28 April 1992
          Page count
          Pages: 9
          Original Paper

          Vision sciences,Ophthalmology & Optometry,Pathology
          K+ ,Superoxide dismutase,Free radicals,Rat retina,Na+ ,Ca2+ ,Mg2+ ,Extract of Ginkgo biloba,Allopurinol,Ischemia,Reperfusion


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