As norepinephrine is a potent hepatocyte comitogen through binding to the α1-adrenergic receptor, we have examined mRNA levels of the α1a- and α1b-adrenergic receptor subtypes in normal and regenerating rat hepatocytes as well as in several different rat hepatoma cell lines. All rat hepatomas examined lacked both α1a- and α1b-receptor message and receptor binding in radioligand binding experiments, suggesting that the growth of dedifferentiated neoplastic rat hepatocytes is not regulated by the α1-adrenergic receptor. Interestingly, unlike the rat hepatomas analyzed, the human hepatocellular carcinoma cell line, HepG2, was positive for both α1a and α1b message at 4.5 kb, yet this cell line lacked receptor binding in radioligand binding assays. While normal and regenerating liver is negative for α1a -receptor expression, it is positive for α1b expression and is characterized by the presence of two bands at approximately 4.0 and 3.2 kb which peaked between 20 and 48 h after partial hepatectomy. A dramatic decrease in message level of the lower band and the continued presence of the upper band between 6 and 12 h after partial hepatectomy, and before the peak in DNA synthesis in regenerating rat liver, may correspond with observed differences in α1-receptor function during liver regeneration.

Keywords:
α-Adrenergic receptors, Hepatocytes, Liver
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.