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Updated: Aug 29, 2026

Mesenteric Artery Contraction and Relaxation Studies Using Automated Wire Myography
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Published on: September 22, 2011

Morphine potentiates dextromethorphan-induced vasodilation in rat superior mesenteric artery

Saadet Inan1, Ronald J Tallarida

  • 1Department of Pharmacology and Center for Substance Abuse Research, Temple University School of Medicine, 3420 N. Broad St., Philadelphia, PA 19140, USA.

European Journal of Pharmacology
|January 31, 2004
PubMed

Insights

Morphine and dextromethorphan show synergistic relaxation effects on the superior mesenteric artery, a finding blocked by naloxone. This interaction was specific to the mesenteric artery, not observed in other blood vessels.

Area of Science:

  • Pharmacology
  • Vascular Biology
  • Drug Interactions

Background:

  • Opioids like morphine and antitussives like dextromethorphan have complex vascular effects.
  • Understanding their combined action is crucial for predicting clinical outcomes.

Purpose of the Study:

  • To investigate the synergistic effects of morphine and dextromethorphan on the superior mesenteric artery.
  • To explore the role of naloxone and the endothelium in this interaction.

Main Methods:

  • Isolated superior mesenteric artery rings were used in a muscle bath setup.
  • Vascular tension was recorded using a force transducer.
  • Dose-response curves for dextromethorphan, morphine, and their combination were generated.

Main Results:

  • Dextromethorphan caused dose-dependent relaxation; morphine alone had no effect.
  • A significant synergistic relaxation (factor of 3.7) was observed with the morphine-dextromethorphan combination.
  • Naloxone abolished the synergism, while endothelial removal only slightly attenuated it.
  • Additive interactions were noted in the carotid artery and aorta, unlike the mesenteric artery.

Conclusions:

  • Morphine and dextromethorphan exhibit potent, naloxone-reversible synergism in the superior mesenteric artery.
  • This synergistic effect appears to be endothelium-independent and specific to certain vascular beds.

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