At 1-5 mcg/kg/min, dopamine primarily causes dilation of which vascular beds?

• A. Renal and mesenteric dilation
• B. Cerebral and coronary dilation
• C. Pulmonary and hepatic dilation
• D. Peripheral and cutaneous dilation

Answer: (A)

At the lowest dose range, dopamine mainly stimulates dopamine D1 receptors in vascular smooth muscle. Activation of these receptors causes vasodilation in renal and mesenteric (splanchnic) beds by increasing cAMP within the smooth muscle, leading to relaxation. This dose-dependent effect is why renal perfusion and GFR may improve with low-dose dopamine. As the dose increases, dopaminergic effects give way to β1-adrenergic effects (increasing heart rate and contractility) and then α-adrenergic effects (vasoconstriction). So, at 1–5 mcg/kg/min, the primary vascular dilation occurs in the renal and mesenteric territories.