Mirfentanil antagonizes morphine-induced suppression of splenic NK activity in mice

Daniel J.J. Carr, Linda L. Brockunier, Mace Scott, Jerome R. Bagley, Charles P. France

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Mirfentanil [N-(2-pyrazinyl)-N-(1-phenethyl-4-piperidinyl)-2-furamide] was studied for its antinociceptive and immunomodulatory effects in mice. Mirfentanil (1.0-32.0 mg/kg) increased tail-flick latency to a thermal stimulus and this effect was antagonized (94 ± 2%) by naltrexone (10.0 mg/kg). Unlike naltrexone, the delta opioid selective antagonist naltrindole (20.0 mg/kg) had no effect on mirfentanil-induced analgesia. In a dose-dependent fashion, the μ-selective antagonists β-funaltrexamine (1.0-40.0 mg/kg) and naloxonazine (1.0-35.0 mg/kg) blocked mirfentanil (10.0 mg/kg)-induced analgesia up to 75% of the maximum analgesic effect. Norbinaltorphimine (10.0 mg/kg) partially blocked (35%) the maximum analgesic effect following mirfentanil (10.0 mg/kg) administration. Single doses of mirfentanil (0.1-32.0 mg/kg) had no effect on splenic NK activity. However, preadministration of mirfentanil (1.0-10.0 mg/kg) blocked morphine-induced suppression of splenic NK activity. Collectively, the results suggest that mirfentanil is a novel opioid that induces antinociception predominately through μ opioid receptors but, unlike morphine or fentanyl, does not suppress splenic NK activity.

Original languageEnglish (US)
Pages (from-to)9-16
Number of pages8
Issue number1
StatePublished - Aug 1996
Externally publishedYes


  • Analgesia
  • Immunomodulation
  • Mirfentanil
  • Morphine
  • Natural killer activity
  • Opioid

ASJC Scopus subject areas

  • Pharmacology


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