Denopamine (beta 1-selective adrenergic receptor agonist) and isoproterenol (non-selective beta-adrenergic receptor agonist) equally increase heart rate and myocardial oxygen consumption in dog heart.
The effects of denopamine (a beta 1-selective adrenergic receptor agonist) and isoproterenol (a non-selective beta-adrenergic receptor agonist) on heart rate, left ventricular contractility, and left ventricular oxygen consumption (VO2) at the same left ventricular volume were compared in excised cross-circulated dog hearts. Denopamine and isoproterenol increased heart rate and VO2 to a comparable extent at a comparably increased contractility. Moreover, the oxygen cost of contractility which quantifies VO2 for excitation-contraction coupling was the same between the two agents. These findings contradict the previously reported smaller increases in heart rate and VO2 by denopamine than by isoproterenol in open-chest dog hearts, which have been mainly attributed to the beta 1-selectivity of denopamine. Our results suggest that in isolated and denervated hearts, the degree of beta 1-selectivity of a beta-agonistic agent does not directly determine the relative potencies of its inotropic and chronotropic effects and the oxygen cost of contractility.
Department of Cardiovascular Dynamics National Cardiovascular Center Research Institute, Osaka, Japan.
S
S
Futaki
Y
Y
Goto
Y
Y
Ohgoshi
H
H
Yaku
O
O
Kawaguchi
H
H
Suga
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004983:Ethanolamines / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D012044:Regression Analysis; D013268:Stimulation, Chemical; D016277:Ventricular Function, Left / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D007545:Isoproterenol; C037293:denopamine