Skip to main content
Advertisement

Main menu

  • Home
  • Articles
    • Current Issue
    • Fast Forward
    • Latest Articles
    • Archive
  • Information
    • Instructions to Authors
    • Submit a Manuscript
    • FAQs
    • For Subscribers
    • Terms & Conditions of Use
    • Permissions
  • Editorial Board
  • Alerts
    • Alerts
    • RSS Feeds
  • Virtual Issues
  • Feedback
  • Other Publications
    • Drug Metabolism and Disposition
    • Journal of Pharmacology and Experimental Therapeutics
    • Molecular Pharmacology
    • Pharmacological Reviews
    • Pharmacology Research & Perspectives
    • ASPET

User menu

  • My alerts
  • Log in
  • My Cart

Search

  • Advanced search
Molecular Pharmacology
  • Other Publications
    • Drug Metabolism and Disposition
    • Journal of Pharmacology and Experimental Therapeutics
    • Molecular Pharmacology
    • Pharmacological Reviews
    • Pharmacology Research & Perspectives
    • ASPET
  • My alerts
  • Log in
  • My Cart
Molecular Pharmacology

Advanced Search

  • Home
  • Articles
    • Current Issue
    • Fast Forward
    • Latest Articles
    • Archive
  • Information
    • Instructions to Authors
    • Submit a Manuscript
    • FAQs
    • For Subscribers
    • Terms & Conditions of Use
    • Permissions
  • Editorial Board
  • Alerts
    • Alerts
    • RSS Feeds
  • Virtual Issues
  • Feedback
  • Visit molpharm on Facebook
  • Follow molpharm on Twitter
  • Follow molpharm on LinkedIn
Abstract

p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor.

M A Gerhardt, S M Wade and R R Neubig
Molecular Pharmacology August 1990, 38 (2) 214-221;
M A Gerhardt
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
S M Wade
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
R R Neubig
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Info & Metrics
  • eLetters
  • PDF
Loading

Abstract

The binding properties of p-[125I]iodoclonidine [( 125I]PIC) to human platelet membranes and the functional characteristics of PIC are reported. [125I]PIC bound rapidly and reversibly to platelet membranes, with a first-order association rate constant (kon) at room temperature of 8.0 +/- 2.7 x 10(6) M-1 sec-1 and a dissociation rate constant (koff) of 2.0 +/- 0.8 x 10(-3) sec-1. Scatchard plots of specific [125I]PIC binding (0.1-5 nM) were linear, with a Kd of 1.2 +/- 0.1 nM. [125I]PIC bound to the same number of high affinity sites as the alpha 2-adrenergic receptor (alpha 2-AR) full agonist [3H] bromoxidine (UK14,304), which represented approximately 40% of the sites bound by the antagonist [3H]yohimbine. Guanosine 5'-(beta, gamma-imido)triphosphate greatly reduced the amount of [125I]PIC bound (greater than 80%), without changing the Kd of the residual binding. In competition experiments, the alpha 2-AR-selective ligands yohimbine, bromoxidine, oxymetazoline, clonidine, p-aminoclonidine, (-)-epinephrine, and idazoxan all had Ki values in the low nanomolar range, whereas prazosin, propranolol, and serotonin yielded Ki values in the micromolar range. Epinephrine competition for [125I]PIC binding was stereoselective. Competition for [3H]bromoxidine binding by PIC gave a Ki of 1.0 nM (nH = 1.0), whereas competition for [3H]yohimbine could be resolved into high and low affinity components, with Ki values of 3.7 and 84 nM, respectively. PIC had minimal agonist activity in inhibiting adenylate cyclase in platelet membranes, but it potentiated platelet aggregation induced by ADP with an EC50 of 1.5 microM. PIC also inhibited epinephrine-induced aggregation, with an IC50 of 5.1 microM. Thus, PIC behaves as a partial agonist in a human platelet aggregation assay. [125I]PIC binds to the alpha 2B-AR in NG-10815 cell membranes with a Kd of 0.5 +/- 0.1 nM. [125I]PIC should prove useful in binding assays involving tissues with a low receptor density or in small tissue samples and in studies of cloned and expressed alpha 2-AR.

MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years. 

Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page. 

 

  • Click here for information on institutional subscriptions.
  • Click here for information on individual ASPET membership.

 

Log in using your username and password

Forgot your user name or password?

Purchase access

You may purchase access to this article. This will require you to create an account if you don't already have one.
PreviousNext
Back to top

In this issue

Molecular Pharmacology
Vol. 38, Issue 2
1 Aug 1990
  • Table of Contents
  • Table of Contents (PDF)
  • Index by author
  • Back Matter (PDF)
  • Editorial Board (PDF)
  • Front Matter (PDF)
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for sharing this Molecular Pharmacology article.

NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. We do not retain these email addresses.

Enter multiple addresses on separate lines or separate them with commas.
p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor.
(Your Name) has forwarded a page to you from Molecular Pharmacology
(Your Name) thought you would be interested in this article in Molecular Pharmacology.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Abstract

p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor.

M A Gerhardt, S M Wade and R R Neubig
Molecular Pharmacology August 1, 1990, 38 (2) 214-221;

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Share
Abstract

p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor.

M A Gerhardt, S M Wade and R R Neubig
Molecular Pharmacology August 1, 1990, 38 (2) 214-221;
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
  • Info & Metrics
  • eLetters
  • PDF

Related Articles

Cited By...

Similar Articles

  • Home
  • Alerts
Facebook   Twitter   LinkedIn   RSS

Navigate

  • Current Issue
  • Fast Forward by date
  • Fast Forward by section
  • Latest Articles
  • Archive
  • Search for Articles
  • Feedback
  • ASPET

More Information

  • About Molecular Pharmacology
  • Editorial Board
  • Instructions to Authors
  • Submit a Manuscript
  • Customized Alerts
  • RSS Feeds
  • Subscriptions
  • Permissions
  • Terms & Conditions of Use

ASPET's Other Journals

  • Drug Metabolism and Disposition
  • Journal of Pharmacology and Experimental Therapeutics
  • Pharmacological Reviews
  • Pharmacology Research & Perspectives
ISSN 1521-0111 (Online)

Copyright © 2021 by the American Society for Pharmacology and Experimental Therapeutics