Muscarinic Acetylcholine receptors are selectively blocked by :
a) atropine
b) C5
c) muscarine
d) curare and C6
e) nicotine
Answer:
a) atropine
Explanation
Acetylcholine (ACh) is the chemical neurotransmitter for both peripheral and central cholinergic receptors. These cholinoceptive sites are further divided into nicotinic and muscarinic ACh receptors because of its relative specificity of action toward cholinomimetic [L(+) muscarine, S(-) nicotine] and cholinergic blocking agents (d-tubocurarine, atropine). Nicotinic ACh receptors are selectively stimulated by nicotine and blocked by curare, C6 and C10. Muscarinic ACh receptors are activated by L (+) muscarine and blocked by atropine. It should be noted that nicotine acts at nicotinic sites to produce stimulation in low doses blockade in high doses.