This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemical Messengers: Receptors, Subject name: Physiology
Which muscarinic receptor causes dilatation of vessels- 
Select and explain. 
A. M1, B. M2, C. m3, D. m4
C: m3
Answer: C: m3 
Explanation: Ans. is 'c' i.e., M3 o M3 receptors are found in vessels (endothelium). Activation of these recepters causes vasodilatation by release of EDRF (NO).o M3 receptors are unique muscarinic receptors in that their activation does not cause release of acetylcholine, rather causes relcease of EDRF (NO).