Important cholinoceptors in the ANS and peripheral motor nervous system

Question 1

M1 RECEPTOR

• Location
• Mechanism
• 2nd messenger
• Action (example)

Answer 1

M1 RECEPTOR

• Location: nerve endings
• Mechanism: Gq-coupled
• 2nd messenger: increase IP3, DAG cascade
• Action: activate myenteric plexus

Question 2

M2 RECEPTOR

• Location
• Mechanism
• 2nd messenger
• Action (example)

Answer 2

M2 RECEPTOR

• Location: heart, some nerve endings
• Mechanism: Gi- coupled
• 2nd messenger: decrease cAMP, activate K+ channels
• Action: slow SA node

Question 3

M3 RECEPTOR

• Location
• Mechanism
• 2nd messenger
• Action (example)

Answer 3

M3 RECEPTOR

• Location: smooth muscle, glands, endothelium
• Mechanism: Gq- coupled
• 2nd messenger: increase IP3, DAG cascade
• Action (example): contract detrusor muscle, increase salivation

Question 4

N, SUBTYPE N

• Location
• Mechanism
• 2nd messenger
• Action (example)

Answer 4

N, SUBTYPE N
nicotinic receptor

• Location: ANS ganglia
• Mechanism: Na-K channel
• 2nd messenger: Na+
• Action: depolarizes postganglionic fiber, evokes AP

Question 5

N, SUBTYPE M

• Location
• Mechanism
• 2nd messenger
• Action (example)

Answer 5

N, SUBTYPE M
nicotinic receptor

• Location: Neuromuscular end plate
• Mechanism: Na-K channel
• 2nd messenger: Na+
• Action: depolarizes muscle cell, evokes AP and contraction