This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Dopamine at 1-2 Microgram/ Kg/ min produces? 
Select and explain. 
A. Renal vasodilatation, B. Positive ionotropic effect, C. Mesenteric vasoconstriction, D. Generalised vasoconstriction
A: Renal vasodilatation
Answer: A: Renal vasodilatation 
Explanation: Ans. is 'a' i.e., Renal vasodilatation Dopamine produces dose dependent action: At low dose (1-2 ug/kg/min) causes dilation of renal and mesentric vessels - often referred as renal dose. At moderately high dose (2-10 ug/kg/min) produces a positive ionotropic effect by stimulating b1 receptor on hea - cardiac dose. At high doses (> 10 ug/kg/min) produces vasoconstriction by stimulating a1 receptors - vascular dose.