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
Apa from release of EDRF, other mechanism of vasodilatory action of acetylcholine is - 
Select and explain. 
A. Direct action of cause vascular smooth muscle relaxation, B. Inhibition of nor-epinephrine release from adrenergic nerve endings, C. Stimulation of platelet aggregation, D. Stimulation of vascular 132 receptors
B: Inhibition of nor-epinephrine release from adrenergic nerve endings
Answer: B: Inhibition of nor-epinephrine release from adrenergic nerve endings 
Explanation: Ans. is 'b' i.e., Inhibition of nor-epinephrine release from adrenergic nerve endings o Most of the blood vessels contain cholinergic M3 receptors on endothelium but no parasympathetic nerve supply. o Exogenously administered ACh can stimulate M3 receptors which results in release of EDRF (NO) from endothelium that causes vasodilatation. o Vasodilation also may occur indirectly due to inhibition of NA release from nerve endings by Ach.