Pharm 6 - Cholinomimetics

Question 1

What is a cholinomimetic

Answer 1

Drug that mimics the action of ACh

Question 2

Muscarinic receptors are which ANS branch?

Answer 2

PNS

Question 3

Muscarine is a selective agonist. What is its antagonist?

Answer 3

Atropine

Question 4

Is more muscarine required to stimulate muscarinic receptors or Nicotinic?

Answer 4

Nicotinic - they are less sensitive to agonist

Question 5

Where are M3 receptors located?

Answer 5

Salivary glands / bronchial/visceral SM / Sweat glands / eye

Question 6

Where are M2 receptors located?

Answer 6

Heart

Question 7

Where are M1 receptors located?

Answer 7

Salivary gland, stomach, CNS

Question 8

Which M receptors are excitatory?

Answer 8

M1 and M3 (IP3 –> DAG)

Question 9

Which M receptors are inhibitory?

Answer 9

M2 (cAMP)

Question 10

What type of receptor are muscarinic receptors?

Answer 10

G protein coupled receptors

Question 11

Nicotinic receptors are type 1 receptors meaning?

Answer 11

They are ligand gated ion channels

Question 12

How many subunits do nicotinic receptors have? What does this mean?

Answer 12

5 subunits - means they all have some structural variation

Question 13

What are 3 muscarinic effects on the eye?

Answer 13

1. Constriction of ciliary muscle (promotes near sighted vision)
2. Contraction of spincter papillae - causing pupil constriction and drainage of intraocular fluid
3. Lacrimation

Question 14

Where does aqueous humour drain in the eye?

Answer 14

Canals of Schlemm

Question 15

How can intraocular pressure in eye be reduced?

Answer 15

Stimulate muscarinic receptors - causes contraction of sphincter pupillae

Question 16

In the heart, where are M2 receptors located?

Answer 16

Atria and nodes

Question 17

How does increased muscarinic stimulation to M2 receptors cause decreased HR and CO?

Answer 17

M2 stimulation = decreased cAMP conc = decreased Ca influx (decreases CO), and increased K efflux (decreased HR)

Question 18

Do most blood vessels have PNS innervation?

Answer 18

NO

Question 19

How can M3 receptors act to reduce TPR

Answer 19

ACh acts on M3 receptors on vascular endothelial cells - stimulates NO production

NO induces VSMC relaxation, which decreases TPR

Question 20

What are muscarinic effects on non-vascular SM?

Answer 20

Excitatory

Lung = bronchoconstriction

Gut = increased peristalsis

Bladder = increased emptying

Question 21

What are muscarinic effects on exocrine glands?

Answer 21

Salivation / increased bronchial secretions / increased GI secretions / increased sweating (SNS mediated)

Question 22

What are the 2 types of directly acting cholinomimetic drugs?

Answer 22

1. Choline esters (bethanechol)

2. Alkaloids (pilocarpine)