Effect of isoproterenol on the relationship between regional cyclic amp and local coronary blood flow in the canine myocardium

Johannes Ramirez, Elizabeth Rodriguez, Harvey R. Weiss

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This study was designed to test in the dog heart the hypothesis that local levels of myocardial cyclic AMP (cAMP) would exhibit significant heterogeneity; that this heterogeneity would correlate with local coronary blood flow, and that this association would be increased with isoproterenol stimulation. Anesthetized open-chest dogs were studied during control (n = 7) or isoproterenol (0.5 μg/kg/min) infusion (n = 7) to test this hypothesis. Coronary blood flow was measured with radioactive microspheres, and cAMP was determined with a competitive binding assay using 3H-cAMP. Significant heterogeneity in cAMP existed during basal [592 pmol/g, within-ani- mal coefficient of variation (100 Ö mean/SD) = 45.2%] and isoproterenol stimulated [872 (27.3%)] conditions. Method variability could account for only 28% of the total basal variability. No correlation between local blood flow [87 ml/min/100 g (12.9%)] and local cAMP was found under control conditions. Both coronary blood flow [206 (20.8%)] and cAMP levels increased significantly with isoproterenol stimulation. There was a significant correlation between normalized stimulated blood flow and cAMP: % flow = 0.39 (% cAMP) + 61.3 (r = 0.48, p < 0.0001). We conclude that significant heterogeneity in myocardial cAMP levels exists, and that this heterogeneity correlates with coronary blood flow heterogeneity during isoproterenol stimulation.

Original languageEnglish (US)
Pages (from-to)41-48
Number of pages8
JournalPharmacology
Volume48
Issue number1
DOIs
StatePublished - 1994

All Science Journal Classification (ASJC) codes

  • Pharmacology

Keywords

  • Coronary blood flow
  • Cyclic adenosine monophosphate
  • Dog
  • Isoproterenol
  • β-Adrenergic agonist

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