α-adrenergic effects of dopamine and dobutamine on the coronary circulation

Xue Zheng Dai, Da Guang Chen, Robert J Bache

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17 Scopus citations

Abstract

After β-adrenergic blockade, dopamine causes coronary vasoconstriction that is blocked by nonselective α-adrenergic antagonists. This study was carried out to determine the relative importance of α1- and α2-adrenoceptors in mediating coronary vasoconstriction in response to dopamine. Because dobutamine has been reported to cause α-adrenergic stimulation, the response to dobutamine was also examined. The circumflex coronary artery was cannulated and perfused at a constant blood flow rate in 14 dogs; coronary vasomotor responses were assessed from changes in perfusion pressure. Central effects were eliminated by vagotomy and stellate ganglionectomy; propranolol (1 mg/kg i.v.) was administered to block β-adrenergic effects. The coronary responses to intracoronary bolus doses of dopamine and dobutamine were determined; the effects of selective α1-blockade with prazosin (600μ.g/kg i.v.) and selective α2-blockade with idazoxan or rauwolscine (1-5 μ.g/kg per min intracoronary for 10 min) were examined. Dopamine produced dose-related coronary vasoconstriction; this response was not significantly altered by α1-blockade with prazosin, but was abolished by the addition of α2-adrenergic blockade with idazoxan or rauwolscine. Dobutamine did not produce coronary vasoconstriction at any dose tested. These data demonstrate that coronary vasoconstriction produced by dopamine is mediated through postjunctional α2-adrenergic receptors.

Original languageEnglish (US)
Pages (from-to)82-87
Number of pages6
JournalJournal of Cardiovascular Pharmacology
Volume14
Issue number1
DOIs
StatePublished - Jul 1989

Keywords

  • Adrenergic vasoconstriction
  • Coronary blood flow
  • Dobutamine
  • Dopamine
  • Idazoxan
  • Prazosin

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