This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sympathetic System, Subject name: Pharmacology
Dopamine is preferred over dobutamine in treatment of shock with oliguria because:- 
Select and explain. 
A. It has additional renal vasodilatory effect, B. It increases cardiac output, C. It causes peripheral vasoconstriction only, D. It has prolonged action
A: It has additional renal vasodilatory effect
Answer: A: It has additional renal vasodilatory effect 
Explanation: Dopamine is the drug of choice for cardiogenic shock with oliguric renal failure. It acts on D1 (at a dose of 1-2 mg/kg/ min.), b1 (at 2-10 mg/kg/min.) and a1 (at > 10 mg/kg/min.) receptors. It causes renal vasodilation by acting on D1 receptors and maintains renal perfusion and GFR. Other ionotropic agents like NA cause renal vasoconstriction and thus worsen renal failure.