How are Adrenergic receptor agonists use in cardiac contractility?

Dobutamine and Dopamine positive inotropic and vasodilation, most common is dobutamine other than digoxin by increasing cAMP and activating protein kinase to slow Ca channels increasing entry of Ca into cells Given IV, for short term action for acute HF Act on Beta 1 receptors, drugs of choice for shock given continuous infusion, raises BP and CO (Dopamine) Dobutamine (same, increase CO but lesser extent on vessels and HR, for Congestive HF and inotropic support post cardiac surgery no increase in O2 demand of myocardium)