Adrenergic

Question 1

Norepinephrine operates at?

Answer 1

neuroeffector junction

Question 2

What are the structural characteristics of norepinephrine?

Answer 2

Catechol, Amine, Phenylethyl, R isomer more potent than S

Question 3

Tyrosine is converted to Dopa by?

Answer 3

Tyrosine hydroxylase, iron, folate, oxygen

Question 4

Dopa is converted to Dopamine by?

Answer 4

LAAAD, pyridoxal phosphate

Question 5

Dopamine is converted to Norepinephrine by?

Answer 5

Dopamine beta-hydroxylase, copper, oxygen, vitamin C

Question 6

Where and how is norepinephrine stored?

Answer 6

Presynpatic in vesicles as granules.

Granule consists of 4 ATP: 1 NE, chromagranin, and enzyme dopamine beta-hydroxylase

Question 7

How is NE released?

Answer 7

Action potential results in a depolarization. Calcium passes to nerve endings and vesicle fuses with cell membrane. Released into synpatic area.

Question 8

How is the release of NE regulated?

Answer 8

NE is regulated by alpha-2 receptors. When NE binds it results in a decrease in NE release and biosynthesis, and an increase in reuptake.

Question 9

Where are adrenergic receptors located?

Answer 9

Both pre and post-synpatically

Question 10

All alpha and beta receptors are members of what family?

Answer 10

GPCR g-protein coupled receptor

Question 11

alpha 1 receptors act on what G proteins?

Answer 11

Gq - activation of PLC and hydrolysis of PIP2 to give 2nd messengers DAG and IP3
Gca - regulates calcium channels

Question 12

Alpha 2 receptors act on what G proteins?

Answer 12

Gi - inhibit adenylate cyclase, and decrease formation of cAMP

Question 13

All beta receptors act on what G proteins?

Answer 13

Gs - stimulates adenylate cyclase, and increase cAMP production

Question 14

How is NE terminated?

Answer 14

1. reuptake from the synapse by an active transporter into the presynpatic terminal to be restored in vesicles or broken down by MAO.
2. metabolism
3. loss to circulation

Question 15

Explain the metabolism of NE, EPI.

Answer 15

MAO - aldehyde
Aldehyde reductase - 1 alcohol
COMT - add methyl
Alcohol dehydrogenase
aldehyde dehydrogenase

Question 16

What agents are used to inhibit the biosynthesis of NE?

Answer 16

Metyrosine - binds to tyrosine hydroxylase preventing catalytic activity. This is reversible.

Methyldopa - acts as an alternative substrate for LAAAD. this is converted to methylnorepinephrine, a false neurotransmitter.

Question 17

Alpha 1 receptors are located where? what responses do they mediate?

Answer 17

Located postsyaptic. vasoconstriction, uterine contraction, prostate.
Subtypes A,B,D

Question 18

Alpha 2 receptors are located where? What response do they mediate?

Answer 18

Located presynaptic in CNS. Regulation the release/biosynthesis of NE.
Subtypes A,B,C

Question 19

What are the uses for alpha-1 agonists?

Answer 19

management shock, decongestion, local vasoconstriction, glaucoma, spasticity

Question 20

What are the uses for alpha-2 agonists?

Answer 20

Hypertension, glaucoma, spasticity

Question 21

What are the uses for alpha-1 antagonists?

Answer 21

Mangement of hypertension, BPH

Question 22

What are the uses for alpha-2 antagonists?

Answer 22

Treatment of mild depression

Question 23

How can alpha-1 agonist be classified structurally?

Answer 23

phenethanolamines, imidazoline

Question 24

What do modification of phenethanolamine result in?

Answer 24

n-substituent = binding
A-carbon substituent = selectivity a1 methyl
b-OH group = agonist activity
Meta OH group = alpha selectivity

Question 25

Clonidine acts on which receptors?

Answer 25

alpha 2 a presynpatic in CNS for hypertension

Alpha 2 b in peripheral

Question 26

Tizanidine acts on what receptor?

Answer 26

Alpha 2c presynpatic, inhibit motor neurons resulting in a decreased muscle spasticity

Question 27

This drug is used for sedation in the ICU.

Answer 27

Dexmedetomidine

Question 28

What does phentolamine treat?

Answer 28

Extravasation, diagnosis of pheochromocytoma, reverse soft tissue local anesthesia.