PNS drugs

Question 1

2 main types of cholinergic receptors and mechanism of receptor action

Answer 1

1. muscarinic - GPCR

2. nicotinic - ligand gated ion channels

Question 2

locations of 3 types of M receptors

Answer 2

M1- CNS, autonomic ganglia, glands, enteric nerves
M2- CNS, heart, smooth muscle, autonomic terminals
M3- CNS, smooth muscle (iris, glands, GI) heart

Question 3

functions of 3 types of M receptors

Answer 3

M1- stim juices
M2- SA node slowing, AV node slowing, myocardium slow contraction
M3- smooth muscle contraction

Question 4

location of N receptors (2)

Answer 4

Nm - at neuromuscular junction - skeletal muscle contraction

Nn - autonomic ganglia (firing of post-synaptic neuron), adrenal medulla (secretion of catecholamines)

Question 5

M1,3,5 mechanism of action

Answer 5

Gq > activation of PLC > hydrolysis of PIP has 2 actions

1. IP3 > release of stored calcium > contraction of smooth muscle
2. DAG > activated PKC > phosphorylation of substrate proteins

Question 6

M2,4 mechanism of action

Answer 6

Gi/o > inhibs adenosine cyclase > lower cAMP has 2 actions

1. activation of inward K channels >membrane hyperpolarization> less activity
2. inhibition of neuronal channels

Question 7

3 N receptor actions

Answer 7

1. autonomic - stims postganlionic SNS and PNS neurons
2. adrenal medulla - release catecholamines
3. muscle - contract skeletal muscle

Question 8

what are drugs that turn on PNS

Answer 8

1. parasympathicomimetics
2. cholinergics
3. muscarinic agonists
4. nicotinic agonsists
5. acetylcholinesterase inhibitors

Question 9

what are drugs that turn off PNS

Answer 9

1. parasympatholytics

2. cholinergic, muscarinic, nicotinic antagoinists

Question 10

M receptor agonists

Answer 10

1. Ach
2. muscarine
3. pilocarpine
4. methacholine
5. carbachol

Question 11

issues with Ach

Answer 11

1. endogenous

2. not well absorbed, need large IV doses, doesn’t cross BBB

Question 12

what is methacholine used for and why

Answer 12

diagnosis of bronchial activity - ashtma
- greater duration and no N receptor activity
-

Question 13

what is carbachol

Answer 13

1. M and N actions
2. resitiance to cholinesterase
3. used for glaucoma by causing pupil consrition and draining

Question 14

what is pilocarpine

Answer 14

1. mainly M
2. increase salivation and sweating
3. mostly for glaucoma

Question 15

what is bethanechol

Answer 15

1. M actions
2. resitiance to cholinesterase
3. used for GI and GU motility

Question 16

what is indirect Ach drug

Answer 16

acetylocholinesterase

Question 17

why use

Answer 17

more selective that agonists because selects for sites that actively release Ach
** watch for block and neuromuscular JCT - fatal crisis

Question 18

3 reversible Achase inhibs

Answer 18

1. physostigmine - glaucoma
2. neostigmine - myasthenia gravis treatment
3. edrophonium - short acting

Question 19

what are irreversible Achase inhibs

Answer 19

nerve gasses and pesticides

Question 20

4 nicotine agonists

Answer 20

1. nicotine - multiple effects
2. lobeline - used of nicotine withdrawal
3. arecoline - from betel nut
4. succinylcholin - used of paralysis during surgery because causes depolarizing blockade

Question 21

5 actions of nicotine

Answer 21

1. stim sym ganglia> then stim para ganglia> the parasymp blockade at high doses
2. stim sym fibers to release NE within vacular walls and heart
3. stim adrenal to release Epi
4. stim ADH release
5. tremor and nausea due to crossing BBB

Question 22

4 M receptor antagonists

Answer 22

1. atropine
2. scopolamine
3. glycopyrate
4. ipratropium and tiotropium

Question 23

what does atropine do

Answer 23

belladonna

• decrease secretion
• dilates pupils
• increase HR
• antidote for cholinergic poisoning

Question 24

what does scopolamine do

Answer 24

tertiary amine with CNS effects

- treatment of motion sickness, antiemetic

Question 25

what does glycopyrrolate do

Answer 25

quaternary amine
- less oral secretions
for peptic ulcer disease

Question 26

what does ipratropium and tiotropium

Answer 26

used for COPD and asthma for resp effects

Question 27

what does antimuscarinics do for bladder

Answer 27

calm it down so can use for overactive bladder - esp. M3 antagonist

Question 28

when do we use N receptor antagonists

Answer 28

produce non-depolarizing neuromuscular blockade

- can be used to reverse autonomic blockade associated with ACHase inhibs

Question 29

4 features of neuromuscular blockers

Answer 29

1. non-depolarizing and polarizing types
2. structural analogues of ACH
3. very polar so must be given paraenterally
4. act by blocking cholinergic tranmission between nerve and the muscle receptor

Question 30

what are 2 actions of non-depolarizing blockers

Answer 30

1. low doses act as an antagonist by blocking

2. high doses can enter the pore and and make it even harder to overcome

Question 31

what is mech of depolarizing blockers

Answer 31

bind and depolarize, but then tire it out so no more