Pharmacology

Question 1

What are the steps in Catecholamine synthesis?

Answer 1

In the nerve cytoplasm: Tyrosine is converted to Dopa, Dopa is converted to Dopamine

In vesicle: Dopamine is converted to Norepinephrine

In a vesicle located in the adrenal medulla: Norpepinephrine is converted to Epinephrine

Question 2

How does tyrosine enter the nerve cell?

Answer 2

Through a Na+-dependent tyrosine transporter

Question 3

How do the neurotransmitters become stored in the secretory vesicles?

Answer 3

Vesicular Monoamine Transporter 2 (VMAT-2) transports Norepinephrine, Dopamine, Epinephrine, and serotonin into the vesicles.

Question 4

What is the purpose of the Norepinephrine Transporter (NET) and the Dopamine Transporter (DAT)?

Answer 4

They are responsible for reuptake of Norepinephrine and Dopamine into the neuron from the synaptic cleft to be reused in a subsequent signal transmission.

Question 5

What does the drug Reserpine do?

Answer 5

It blocks the VMAT-2 transporter, preventing storage of neurotransmitters in vesicles

Question 6

What does Cocaine do?

Answer 6

It blocks the Norepinephrine transporter, preventing reuptake of norepinephrine from the synaptic cleft, prolonging norepinephrine signaling.

Question 7

What is the difference in termination of signaling between cholinergic and catecholamine signaling?

Answer 7

Cholinergic signal termination primarily involves the use of enzymes to degrade the signal (acetylcholine esterase)

Catecholamine signaling primarily requires the re-uptake of the neurotransmitter (though some enzymes aid in metabolizing them)

Question 8

What are the enzymes used to metabolize catecholamine signals?

Answer 8

Monoamine Oxidase (MAO)
Catechol-O-methyltransferase (COMT)

Question 9

What is the type of G-protein receptor, what signaling cascade does it employ, what is the target tissue(s), and which ligand(s) is the Alpha-1 receptor responsive to?

Answer 9

Gq receptor
Activates Phospholipase C, IP3, DAG
Found all over the body
Epinephrine >= Norepinephrine (same as Alpha-2 receptor)

Question 10

What is the type of G-protein receptor, what signaling cascade does it employ, what is the target tissue(s), and which ligand(s) is the Alpha-2 receptor responsive to?

Answer 10

Gi receptor
Inhibits adenylyl cyclase, decreasing cAMP
Found all over the body
Epinephrine >= Norepinephrine (same as Alpha-1 receptor)

Question 11

What is the type of G-protein receptor, what signaling cascade does it employ, what is the target tissue(s), and which ligand(s) is the Beta-1 receptor responsive to?

Answer 11

Gs receptor
Promotes adenylyl cyclase, increasing cAMP
Heart and Juxtaglomerular cells
Epinephrine = Norepinephrine

Question 12

What is the type of G-protein receptor, what signaling cascade does it employ, what is the target tissue(s), and which ligand(s) is the Beta-2 receptor responsive to?

Answer 12

Gs receptor
Promotes adenylyl cyclase, increasing cAMP
Smooth Muscle and Skeletal Muscle
Epinephrine&raquo_space; Norpeinephrine

Question 13

What is the type of G-protein receptor, what signaling cascade does it employ, what is the target tissue(s), and which ligand(s) is the Beta-3 receptor responsive to?

Answer 13

Gs receptor
Promotes adenylyl cyclase, increasing cAMP
Adipose tissue
Epinephrine > Norepinephrine

Question 14

What is the rule of thumb regarding the action of Alpha-1 receptors?

Answer 14

They cause all smooth muscle to contract (Vascular smooth muscle: vasoconstriction)

Question 15

What is the rule of thumb regarding the action of Beta-2 receptors?

Answer 15

They cause smooth muscle relaxation (vasodilation, bronchodilation)

Question 16

What is the rule of thumb regarding the action of Muscarinic receptors?

Answer 16

They cause smooth muscle contraction

Question 17

In the heart, what are the main receptors controlling sympathetic/parasympathetic signaling and what are the resulting actions?

Answer 17

Beta-1 receptor acts as the primary sympathetic receptor and causes an increase in heart rate and contractility

M-2 Receptor acts as the primary parasympathetic receptor and causes a decrease in heart rate and contractility

Question 18

In the blood vessels, what are the main receptors controlling sympathetic/parasympathetic signaling and what are the resulting actions?

Answer 18

Alpha-1 receptor acts as the primary sympathetic receptor and causes vasoconstriction

There is no direct parasympathetic innervation, however M-3 receptors in the endothelium induce NO synthesis, which can indirectly cause vasodilation

Question 19

In bronchial/tracheal smooth muscle, what are the main receptors controlling sympathetic/parasympathetic signaling and what are the resulting actions?

Answer 19

Beta-2 receptors act as the primary sympathetic receptors and cause smooth muscle relaxation

M2/M3 are both used as the parasympathetic receptors and cause smooth muscle contraction

Question 20

In bronchial glands, what are the main receptors controlling sympathetic/parasympathetic signaling and what are the resulting actions?

Answer 20

Alpha-1 & Beta-2 receptors are the sympathetic receptors.
Alpha-1 causes decrease in glandular secretion.
Beta-2 causes increase in glandular secretion.

M2/M3 receptors are the parasympathetic receptors and stimulate the glands.

Question 21

What type of receptors are found in the ganglion and target organ for adrenal sympathetic stimulation?

Answer 21

Nicotinic Acetylcholine Receptors

Question 22

How does the barroreceptor reflex work?

Answer 22

Stretch receptors in the aortic arch and carotid sinus detect changes in blood pressure.

Increased blood pressure induces parasympathetic signaling to heart causing a decrease in heart rate

Decreased blood pressure induces sympathetic signaling to heart causing an increase in heart rate and contractility.

Question 23

What is phenylephrine and what is its effect on the barroreceptor reflex?

Answer 23

It is a Alpha-receptor agonist.

Alpha-1 receptors, when activated, cause vasoconstriction which causes an increase in blood pressure

This increase in blood pressure is detected by the stretch receptors in the carotid sinus and aortic arch, which cause parasympathetic signal to be sent to the heart, inducing a decrease in heart rate.

Question 24

What is histamine and what is its effect on the barroreceptor reflex?

Answer 24

Histamine causes smooth muscle relaxation (vasodilation)

Decrease in blood pressure detected by the stretch receptors in the carotid sinus and aortic arch cause a sympathetic signal to be sent to the heart, inducing an increase in heart rate and contractility.

Question 25

What is a Cholinomimetic agent?

Answer 25

A drug that mimics Acetylcholine.

Can either act as a AchR agonist OR Acetylcholinesterase inhibitor

Question 26

What is a Cholinoceptor-blocking agent?

Answer 26

A drug that blocks Acetylcholine Receptor (AchR antagonist)

Question 27

What are Sympathomimetic agents?

Answer 27

Drugs that mimic or enhance alpha- and beta-receptor stimulation

Can act as either:

• Agonist
• Reuptake Inhibitor
• Catecholamine release enhancer

Question 28

What is an Adrenoceptor-blocking agent?

Answer 28

A drug that blocks alpha- and beta-receptors (alpha/beta-receptor antagonist)