<unk>  is a direct-acting agent whose primary activity results from stimulation of the β1-adrenoceptors of the heart, increasing contractility and cardiac output. Since it does not act on dopamine receptors to inhibit the release of norepinephrine (another α1 agonist),<unk>  is less prone to induce hypertension than is dopamine.<unk>  is predominantly a β1-adrenergic agonist, with weak β2 activity, and α1 selective activity, although it is used clinically in cases of cardiogenic shock for its β1 inotropic effect in increasing heart contractility and cardiac output.<unk>  is administered as a racemic mixture consisting of both (+) and (−) isomers; the (+) isomer is a potent β1 agonist and α1 antagonist, while the (−) isomer is an α1 agonist. The administration of the racemate results in the overall β1 agonism responsible for its activity. (+)-Dobutamine also has mild β2 agonist activity, which makes it useful as a vasodilator.
Dobutamine
Adenosine
Adrenaline
Norepinephrine 
Norepinephrine
Epinephrine 
Synephrine
Esmolol