Which receptors are activated by dopamine at high doses (>10 mcg/kg/min)?

Which receptors are activated by dopamine at high doses (>10 mcg/kg/min)?

• A. Alpha1
• B. Alpha1, Beta1, Beta2, DA1
• C. Beta1
• D. DA1

Answer: (B)

Dopamine acts on multiple receptor types in a dose-dependent way, so the highest doses engage several systems. At high doses (>10 mcg/kg/min), alpha-1 receptors are activated, causing peripheral vasoconstriction and increased afterload. Beta-1 receptors are also stimulated, boosting heart rate and myocardial contractility. Dopamine continues to stimulate D1 (DA1) receptors, contributing to renal and mesenteric vasodilation in certain beds, and beta-2 receptor activation can occur at high concentrations as well. The combined effect is enhanced vascular tone from alpha-1, increased cardiac output from beta-1, with DA1 activity still present and some beta-2 involvement. That’s why all four receptor types are listed as activated at high doses.

Dopamine acts on multiple receptor types in a dose-dependent way, so the highest doses engage several systems. At high doses (>10 mcg/kg/min), alpha-1 receptors are activated, causing peripheral vasoconstriction and increased afterload. Beta-1 receptors are also stimulated, boosting heart rate and myocardial contractility. Dopamine continues to stimulate D1 (DA1) receptors, contributing to renal and mesenteric vasodilation in certain beds, and beta-2 receptor activation can occur at high concentrations as well. The combined effect is enhanced vascular tone from alpha-1, increased cardiac output from beta-1, with DA1 activity still present and some beta-2 involvement. That’s why all four receptor types are listed as activated at high doses.