The proteolytic conversion of oxytocin and Arg8-vasopressin by purified rat thymocytes was studied at 37°C and physiological pH 7.4. The formed peptide fragments were isolated by high performance liquid chromatography and characterized by amino acid analysis. When oxytocin was incubated with rat thymocytes, oxytocin 1-8 and oxytocin 1–7 were isolated. In contrast, only Arg8-vasopressin 1–8 was found when Arg8-vasopressin was incubated with thymocytes. The formation of oxytocin 1-8, oxytocin 1–7 and Arg8-vasopressin 1–8 was prevented partially by 10–3M phenylmethylsulfonyl fluoride and iodoacetamide, and abolished by 0.5 × 10–3M Zn2+ and Hg2+ ions and 10–3M o-phenanthroline, but not by 10–5M leupeptin, lima bean trypsin inhibitor, trasylol, captopril and phosphoramidon. 0.5 × 10-3M EDTA was without effect on the formation of oxytocin 1–8 and Arg8-vasopressin 1-8 but increased by about 30% the formation of oxytocin 1–7. The results suggest that proteases capable of metabolizing oxytocin and Arg8-vasopressin are localized in the thymocyte surface membrane. Since oxytocin and vasopressin are synthetized by thymic epithelial cells and exert several actions on thymocytes, these proteases may play a physiological role in the inactivation of neurohypophyseal peptides at the thymocyte level.

Keywords:
Oxytocin, Vasopressin, Proteolysis, Thymocytes
This content is only available via PDF.
© 1992 S. Karger AG, Basel
1992
Copyright / Drug Dosage / Disclaimer
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.
You do not currently have access to this content.