Methacholine has maximum agonist action at which of the following cholinergic receptors?: (A) M1, (B) M2, (C) M3, (D) M4
Answer is B. Methacholine is a non selective muscarinic agonist. It has maximum agonist action on M2 receptor Relative Lee selective agonist of cholinergic receptor are: M1 selective: Oxotremorine M2 selective:metha methach ME selective: bethanechol Ref- katzung 12/e p100; KDT 7/e p101