Acetylcholine receptors

Question 1

Activation of muscarinic receptors on presynaptic autonomic nerves causes..

Answer 1

Inhibition of neurotransmisison

Question 2

Subtypes of muscarinic receptors

Answer 2

M1-M5

Question 3

Which muscarinic receptors are coupled with Gq proteins and mechanism of receptor activation

Answer 3

M1, M3 and M5 are coupled with Gq proteins.
Activation stimulates phospholipase C and formation of inositol triphosphate + diacylglycerol. IP3 then causes calcium release in the cell.

Question 4

M1 receptors - locations (3)

Answer 4

Autonomic ganglia
Presynaptic nerve terminals
CNS

Question 5

M3 receptors - locations (3)

Answer 5

Smooth muscles
Glands
Vascular smooth muscle

Question 6

Effects of M1, M3 and M5 receptor activation

Answer 6

Smooth muscle: contraction.
Exocrine glands: secretion.
Vascular endothelial cells: nitric oxide synthesis and vascular smooth muscle relaxation

Question 7

Which muscarinic receptors are coupled with Gαi proteins and mechanism of receptor activation

Answer 7

M2 and M4 are coupled with Gαi proteins .

Activation inhibits adenylate cyclase which decreases cAMP levels. Also increases potassium efflux.

Question 8

M2 recceptors - locations (2)

Answer 8

Sinoatrial and atrioventricular nodes in cardiac tissue

Question 9

Effects of M2 receptor activation

Answer 9

Slowing of heart rate and conduction

Question 10

Types of nicotinic receptors and effects of activation

Answer 10

Muscle type receptor - Muscle contraction (through calcium release).
Ganglionic type receptor - Neuronal excitation (neurotransmitter release).
CNS type receptor - Neuronal excitation.

Question 11

Nicotinic receptors - mechanism

Answer 11

They are ligand-gated sodium channels, causing sodium influx and membrane depolarization