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: Physiology
Relaxation of mesangial cells of the kidney is brought about by 
Select and explain. 
A. cAMP, B. Endothelin, C. PGF2, D. Vasopressin
A: cAMP
Answer: A: cAMP 
Explanation: Substances causing relaxation of mesangial cells
-        ANP
-        Dopamine
-        PGE2
-        cAMP
Substances causing contraction of mesangial cells
-        Endothelin
-        Vasopressin
-        PGF2
-        Angiotensin II
-        Norepinephrine
-        PAF
-        PDGF
-        Thromboxane A2
-        Leukotrienes C4, D4
-        Histamine