Adrenergic Stimulants and Antiadrenergics

Question 1

How do most postganglionic neurons in the SNS signal the target?

Answer 1

Through release of EPI or NE

Question 2

What are the 5 steps of the EPI and NE life cycle? And where do they occur?

Answer 2

1. Synthesis (presynaptic cell)
2. Storage (presynaptic cell)
3. Release (presynaptic cell)
4. Receptor binding (postsynaptic cell)
5. Disposition (synaptic cleft; terminates signal)

Question 3

What happens in the synthesis step (1st) of the EPI/NE life cycle?

Answer 3

Enzyme dopamine-B-hydroxylase uses precursor dopamine to make NE. EPI is a further enzymatic product of the metabolism of NE by phenylethanolamine N-methyltransferase

Question 4

What happens in the storage step (2nd) of the EPI/NE life cycle?

Answer 4

NE or EPI is loaded into synaptic vesicles where it is protected from degradation and also kept in a ready to release format

Question 5

What happens in the release step (3rd) of the EPI/NE life cycle?

Answer 5

Occurs in response to action potential that signals synaptic vesicle fusion with the synaptic membrane. NE or APE is released in the synaptic cleft.

Question 6

What happens in the receptor binding step (4th) of the EPI/NE life cycle?

Answer 6

There are 2 major classes of adrenergic receptors: alpha adrenergic receptors and beta adrenergic receptors

Question 7

What happens in the disposition step (5th) of the EPI/NE life cycle?

Answer 7

Occurs through reuptake of neurotransmitter into presynaptic cell wall where it is recycled. This terminates the signal. The reuptake transporter is called the Nerpinephrine Reuptake Transporter (NET)

Question 8

What are the 2 types of adrenergic receptors?

Answer 8

1. alpha (a1, a2) - Mainly excitatory [exception of a2]
2. beta (B1, B2, B3). - Mainly inhibitory [exception of B1)

• • a1 and B1 = excitatory
• *a2 and B2 = inhibitory

Question 9

Where is a1 found?

Answer 9

Smooth muscle

Question 10

Where is a2 found?

Answer 10

nerve terminals (presynaptic, inhibits NE release)

Question 11

Where is B1 found?

Answer 11

Heart

Question 12

Where is B2 found?

Answer 12

Lungs, GI tract, uterus, vascular smooth muscle, liver, skeletal muscle

Question 13

Where is B3 found?

Answer 13

Fat cells

Question 14

T/F: Activation of the receptor can either activate the target organ, or inactivate it (depending on the type of receptor on the organ)

Answer 14

True

Question 15

What is the name for drugs that activate the SNS?

Answer 15

Sympathomimetic

Question 16

What is asthma characterized by?

Answer 16

hyperreactiveitiy of airways - amount of muscarinic agonist (methocholine) required to decrease exhales air volume by 20% is about 1%-2% of what is required in a non-asthmatic to cause equivalent airway resistance

Question 17

What are the 4 clinic hallmarks?

Answer 17

Recurrent bouts of:

1. Coughing
2. Wheezing
3. Shortness of breath
4. Chest tightness

Question 18

Explain the pathogenesis of asthma

Answer 18

1. Constriction of smooth muscle surrounding airway
2. Swelling of mucosal lining
3. Generation of abnormally thick mucous

Question 19

How do we treat the constriction of the muscles surrounding the airways?

Answer 19

Bronchodilators

Question 20

What adrenergic receptor is responsible for acting on the muscle in the lungs?

Answer 20

B2 (inhibit contraction)

Question 21

What drugs are adrenergic receptor agonists?

Answer 21

1. Epinephrine
2. Pseudoephedrine
3. Clonidine
4. Dobutamine
5. Albuterol

Question 22

What drugs are indirectly acting adrenergic agonists?

Answer 22

1. Amphetamine

2. Cocaine

Question 23

G-protein coupled receptors role

Answer 23

Allow transduction of signal by releasing the stimulatory G-protein complex when bound by EPI or NE

Question 24

Adrenergic antagonists compete with ____ for binding to the receptor.

Answer 24

NE or EPI

Question 25

______ causes an opposite effect to activation of the SNS.

Answer 25

Adrenergic receptor antagonists

Question 26

What antagonist drugs act on adrenergic receptors?

Answer 26

1. Prazosin
2. Propranolol
3. Nadolol
4. Metoprolol

Question 27

What drug is an indirectly acting adrenergic antagonist?

Answer 27

Guanethidine