Peripheral δ-opioid receptors attenuate the exercise pressor reflex

Anna K. Leal, Katsuya Yamauchi, Joyce Kim, Victor Ruiz-Velasco, Marc P Kaufman

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

In rats with ligated femoral arteries, the exercise pressor reflex is exaggerated, an effect that is attenuated by stimulation of peripheral μ-opioid receptors on group IV metabosensitive afferents. In contrast, δ-opioid receptors are expressed mostly on group III mechanosensitive afferents, a finding that prompted us to determine whether stimulation of these opioid receptors could also attenuate the exaggerated exercise pressor reflex in "ligated" rats. We found femoral arterial injection of [D-Pen2,D-Pen5]enkephalin (DPDPE; 1.0 μg), a δ-opioid agonist, significantly attenuated the pressor and cardioaccelerator components of the exercise pressor reflex evoked by hindlimb muscle contraction in both rats with ligated and patent femoral arteries. DPDPE significantly decreased the pressor responses to muscle mechanoreflex activation, evoked by tendon stretch, in ligated rats only. DPDPE (1.0 (μg) had no effect in either group on the pressor and cardioaccelerator responses to capsaicin (0.2 μg), which primarily stimulates group IV afferents. DPDPE (1.0 (μg) had no effect on the pressor and cardioaccelerator responses to lactic acid (24 mM), which stimulates group III and IV afferents, in rats with patent femoral arteries but significantly decreased the pressor response in ligated rats. Western blots revealed the amount of protein comprising the δ-opioid receptor was greater in dorsal root ganglia innervating hindlimbs with ligated femoral arteries than in dorsal root ganglia innervating hindlimbs with patent femoral arteries. Our findings support the hypothesis that stimulation of δ-opioid receptors on group III afferents attenuated the exercise pressor reflex.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume305
Issue number8
DOIs
StatePublished - Oct 15 2013
Externally publishedYes

Keywords

  • Decerebrate rats
  • Neural control of the circulation
  • Peripheral artery disease
  • Thin-fiber muscle afferents

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine
  • Medicine(all)

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