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.
Futaki
S
S
Department of Cardiovascular Dynamics National Cardiovascular Center Research Institute, Osaka, Japan.
Goto
Y
Y
Ohgoshi
Y
Y
Yaku
H
H
Kawaguchi
O
O
Suga
H
H
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