Comparative study between dobutamine and other catecholamines in their effects on the cardiac contraction and rhythm

Abstract

Dobutamine (DOB) showed a dose dependent positive intropic effect on the right ventricular muscle of vagotomized Beagle dogs under pentobarbital anesthesia. Positive inotropic effects of other catecholamines (CA) decreased in the following order; isoproterenol (Iso, 115)>norepinephrine (NE, 15)>DOB (1)> dopamine (DA, 0.36). Brachiocephalic arterial flow was also increased by DOB with a positive inotropic effect in the right ventricular muscle. Though the positive inotropic effect of DOB was slightly decreased by pretreatment with phenoxybenzamine, such was almost completely antagonized by propranolol. Contractions of isolated cat papillary muscle driven by electrical stimulation (12 beats/min) were increased by CA in the following order; Iso (17)>NE (3)>epinephrine (2.5)>DOB (1)>DA (1>). Activity of DOB to induce spontaneous contractions of papillary muscle was weakest among these CA. To determine the arrhythmogenic effect of these CA, coronary ligated Beagle dogs were employed, in which the anterior descending branch of the left coronary artery was ligated. Arrhythmogenic activity of DOB was weaker than other CA employed both in early stages and 48 hr after coronary ligation. DOB shows good potential for treating acute cardiac insufficiency and cardiogenic shock, as effects on heart rate and blood pressure are weaker. © 1977, The Japanese Pharmacological Society. All rights reserved.