Norepinephrine-induced contraction of isolated rabbit bronchial artery: Role of α1- and α2-adrenoceptor activation

A. O.A. Zschauer, M. W. Sielczak, D. A.S. Smith, A. Wanner

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

The contractile effect of norepinephrine (NE) on isolated rabbit bronchial artery rings (150-300 μm in diameter) and the role of α1- and α2-adrenoceptors (AR) on smooth muscle and endothelium were studied. In intact arteries, NE increased tension in a dose-dependent manner, and the sensitivity for NE was further increased in the absence of endothelium. In intact but not in endothelium-denuded arteries, the response to NE was increased in the presence of both indomethacin (Indo; cyclooxygenase inhibitor) and N(G)-nitro-L-arginine methyl ester [L-NAME; nitric oxide (NO) synthase inhibitor], indicating that two endothelium-derived factors, NO and a prostanoid, modulate the NE-induced contraction. The α1-AR antagonist prazosin shifted the NE dose-response curve to the right, and phenylephrine (α1-AR agonist) induced a dose-dependent contraction that was potentiated by L-NAME or removal of the endothelium. The sensitivity to NE was increased slightly by the (α2-AR antagonists yohimbine and idazoxan, and this effect was abolished by Indo or removal of the endothelium. Similarly, contractions induced by UK-14304 (α2-AR agonist) were potentiated by Indo or removal of the endothelium. These results suggest that NE-induced contraction is mediated through activation of α1- and α2-ARs on both smooth muscle and endothelium. Activation of the α1- and α2-ARs on the smooth muscle causes contraction, whereas activation of the endothelial α1- and α2-ARs induces relaxation through release of NO (α1-ARs) and a prostanoid (α2-ARs).

Original languageEnglish (US)
Pages (from-to)1918-1925
Number of pages8
JournalJournal of applied physiology
Volume82
Issue number6
DOIs
StatePublished - Jun 1997

Keywords

  • Endothelium-derived relaxing factors
  • Nitric oxide
  • Prostanoid
  • Vasoconstriction

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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