A lack of potency for the δ‐opioid antagonist naltrindole after microinjection into the rostral ventrolateral medulla of rabbits

David Morilak, Guy Drolet, John Chalmers

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

1. Naltrindole is a novel δ‐opioid antagonist which is highly potent in vitro. We examined the effects on arterial pressure of naltrindole (0.3–300 pmol) after microinjection into the pressor area of the rostral ventrolateral medulla of chloralose‐anaesthetized rabbits. 2. Naltrindole itself had no significant effects on arterial pressure, and only slightly attenuated the hypotensive effect of an exogenous agonist ([d‐Ala2, d‐Leu5]‐enkephalin). This is in contrast to previous demonstration of a marked pressor effect following another δ‐antagonist, ICI 174,864. 3. Thus, naltrindole, tested in vivo against endogenous opioid effects, does not appear to be as potent as it is in vitro, and in this case was virtually ineffective.

Original languageEnglish
Pages (from-to)527-530
Number of pages4
JournalClinical and Experimental Pharmacology and Physiology
Volume17
Issue number7
DOIs
Publication statusPublished - Jul 1990
Externally publishedYes

Keywords

  • blood pressure
  • delta receptors
  • endogenous opioids
  • naltrindole
  • opioid antagonists.

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