At low-dose dopamine, which receptor type is primarily activated?

At low-dose dopamine, which receptor type is primarily activated?

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

Answer: (C)

Dopamine at low doses mainly stimulates dopaminergic D1 receptors in renal and other vascular beds. Activation of these D1 receptors increases cAMP in vascular smooth muscle, causing vasodilation and increased renal blood flow and GFR. Because the dose is low, adrenergic receptors (beta1, beta2, alpha1) aren’t significantly engaged yet; those effects come in at higher doses—beta1 effects on the heart with intermediate doses and alpha1 vasoconstriction at high doses. So the best answer is the D1 (DA1) receptor.

Dopamine at low doses mainly stimulates dopaminergic D1 receptors in renal and other vascular beds. Activation of these D1 receptors increases cAMP in vascular smooth muscle, causing vasodilation and increased renal blood flow and GFR. Because the dose is low, adrenergic receptors (beta1, beta2, alpha1) aren’t significantly engaged yet; those effects come in at higher doses—beta1 effects on the heart with intermediate doses and alpha1 vasoconstriction at high doses. So the best answer is the D1 (DA1) receptor.