Isoproterenol MOA involves which receptor activity?

Isoproterenol MOA involves which receptor activity?

• A. Direct B1 & B2 agonism; 2-3x more potent than epinephrine for B1 receptors
• B. Beta3 agonism
• C. Indirect dopamine release
• D. Direct Alpha1 agonism

Answer: (A)

Isoproterenol works by directly activating beta-adrenergic receptors, mainly beta-1 and beta-2. Direct beta-1 stimulation increases heart rate, contractility, and conduction through the AV node, boosting cardiac output. Beta-2 activation causes vasodilation in skeletal muscle vessels and bronchodilation, which can lower systemic vascular resistance and affect blood pressure. Because it has little to no alpha-1 activity, it does not cause vasoconstriction. It also works through direct receptor activation rather than by releasing dopamine or acting on beta-3 receptors. The strong beta-1 effect is often described as being about 2–3 times more potent at beta-1 receptors than epinephrine, explaining its potent cardiac effects in clinical settings.

Isoproterenol works by directly activating beta-adrenergic receptors, mainly beta-1 and beta-2. Direct beta-1 stimulation increases heart rate, contractility, and conduction through the AV node, boosting cardiac output. Beta-2 activation causes vasodilation in skeletal muscle vessels and bronchodilation, which can lower systemic vascular resistance and affect blood pressure. Because it has little to no alpha-1 activity, it does not cause vasoconstriction. It also works through direct receptor activation rather than by releasing dopamine or acting on beta-3 receptors. The strong beta-1 effect is often described as being about 2–3 times more potent at beta-1 receptors than epinephrine, explaining its potent cardiac effects in clinical settings.