title: Effect of isoproterenol on the relationship between regional cyclic AMP and local coronary blood flow in the canine myocardium.
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 micrograms/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-animal coefficient of variation (100 x 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.
authors.affiliation: Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854-5635.
authors.forename: J
authors.initials: J
authors.lastname: Ramirez
authors.forename: E
authors.initials: E
authors.lastname: Rodriguez
authors.forename: H R
authors.initials: HR
authors.lastname: Weiss
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D003326:Coronary Circulation / Q000187:drug effects*; D000242:Cyclic AMP / Q000378:metabolism*; D004285:Dogs; D005260:Female; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D008863:Microspheres; D009206:Myocardium / Q000201:enzymology
chemical_list: D000242:Cyclic AMP; D007545:Isoproterenol