Effect of α-adrenergic blockade on arrhythmias induced byacute myocardial ischemia and reperfusion in the dog

Roberto Bolli, David J. Fisher, Addison A. Taylor, James B. Young, Richard R. Miller

Research output: Contribution to journalArticlepeer-review


Studies in cats suggest α-adrenergic contributions to arrhythmiasduring myocardial ischemia and reperfusion. The validity of this concept in other species, however, remains uncertain. Thus, 106 chloralose-anesthetized open-chest dogs undergoing a 25 min coronary artery occlusion followed by reperfusion received saline (n=52), prazosin (1 mg/kg, n=26), phentolamine (5 mg/kg, n=18), or phentolamine (same dose)+propranolol (1 mg/kg, n=10). Alpha-blockade was confirmed by α-agonist dose-response studies. In phentolamine-treated dogs, arterial pressure and heart rate were kept constant to prevent exacerbation of ischemia. Control and treated groups were comparable with respect to variables known to affect arrhythmias, such as size of occluded and reperfused vascular beds, coronary collateral flow, severity of ischemia estimated from intramyocardial CO2 tension, and peak reactive hyperemia. During coronary occlusion, the number of single premature ventricular complexes was reduced by phentolamine (P<0.01), but not by prazosin or phentolamine+propranolol; no treatment affected the total number of couplets, ventricular tachycardia episodes and ventricular ectopic complexes, or the incidence of ventricular tachycardia and ventricular fibrillation. During coronary reperfusion, arrhythmias did not differ in control and treated groups. Thus, selective α1-(prazosin), nonselective α1- and α2-(phentolamine), and combined α- and β-blockade (phentolamine+propranolol) failed to attenuate complex arrhythmias induced by acute myocardial ischemia and reperfusion. Alpha-adrenergic mechanisms appear unimportant in the genesis of these arrhythmias in the canine model.

Original languageEnglish (US)
Pages (from-to)1101-1117
Number of pages17
JournalJournal of Molecular and Cellular Cardiology
Issue number12
StatePublished - Dec 1984


  • Acute myocardial ischemia
  • Alpha-adrenergic blockade
  • Alpha-adrenergic receptors
  • Arrhythmias
  • Coronary artery occlusion
  • Coronary artery reperfusion
  • Phentolamine
  • Prazosin
  • Propranolol

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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