Which dose range of dopamine primarily stimulates beta-1 receptors?

Which dose range of dopamine primarily stimulates beta-1 receptors?

• A. 0.5 to 3 µg/kg/min
• B. 3 to 10 µg/kg/min
• C. 10 to 20 µg/kg/min
• D. 20 to 50 µg/kg/min

Answer: (B)

Dopamine has dose-dependent receptor effects. At low doses it mainly stimulates dopaminergic D1 receptors, causing vasodilation in renal and mesenteric beds and increasing renal perfusion. At moderate doses, beta-1 receptors in the heart are activated, boosting heart rate and contractility to raise cardiac output. At high doses, alpha-1 receptors predominate, leading to vasoconstriction and higher systemic vascular resistance. The range that primarily engages beta-1 receptors is 3 to 10 µg/kg/min, where inotropy and chronotropy are enhanced with less vasoconstrictive effect. Doses below this range favor D1 effects, while higher doses shift toward alpha-1 vasoconstriction with less beta-1 influence.

Dopamine has dose-dependent receptor effects. At low doses it mainly stimulates dopaminergic D1 receptors, causing vasodilation in renal and mesenteric beds and increasing renal perfusion. At moderate doses, beta-1 receptors in the heart are activated, boosting heart rate and contractility to raise cardiac output. At high doses, alpha-1 receptors predominate, leading to vasoconstriction and higher systemic vascular resistance. The range that primarily engages beta-1 receptors is 3 to 10 µg/kg/min, where inotropy and chronotropy are enhanced with less vasoconstrictive effect. Doses below this range favor D1 effects, while higher doses shift toward alpha-1 vasoconstriction with less beta-1 influence.