Autonomic Pharmacology 2

Question 1

List the events that occur at the adrenergic terminal, starting from its synthesis.

Answer 1

1. Tyr transported in (Na+ dependent carrier)
2. Tyr –> dihydroxyphenylalanine (DOPA) by TYROSINE HYDROXYLASE
3. DOPA –> dopamine (DA) by DOPA DECARBOXYLASE
4. DA transported into vesicles by vesicular monoamine transporter
5. DA –> NA in vesicle by DOPAMINE-beta-HYDROXYLASE
6. Ca-dependent fusion of vesicles and release of NA

Question 2

What 2 drugs will release NA from vesicles at an adrenergic terminal?

Answer 2

amphetamine and tyramine

Question 3

What rate-limiting step at the adrenergic terminal is blocked by alpha-methyltyrosine?

Answer 3

tyrosine hydroxylase (Tyr –> DOPA)

Question 4

Draw the catechol structure.

Answer 4

check it

Question 5

What are the 2 types of receptors that NA binds to?

Answer 5

alpha-adrenoreceptors and beta-adrenoreceptors

Question 6

What are the 2 methods used to inactivate/terminate the effects of NA in the terminal?

Answer 6

diffusion and uptake

Question 7

What is the difference between uptake 1 and uptake 2 in terms of NA termination at the synaptic cleft?

Answer 7

uptake 1 = into terminals
uptake 2 = into postsynaptic cells

Question 8

What 2 drugs block uptake 1 at adrenergic terminals?

Answer 8

cocaine and tricyclic antidepressants

Question 9

What enzyme metabolizes NA (and other catecholamines) in mitochondria of nerve terminals?

Answer 9

monoamine oxidase (MAO)

Question 10

What enzyme metabolizes NA (and other catecholamines) taken up into the liver?

Answer 10

catechol-o-methyl transferase (COMT)

Question 11

TRUE or FALSE: adrenoreceptors can be either ionotropic or metabotropic.

Answer 11

FALSE: only metabotropic

Question 12

Is alpha1 mainly a postsynaptic or presynaptic adrenoreceptor?

Answer 12

postsynaptic

Question 13

What is the target effect of alpha1 adrenoreceptor binding?

Answer 13

vascular smooth muscle contraction

Question 14

Is NA binding at alpha1 adrenoreceptor excitatory or inhibitory?

Answer 14

excitatory

Question 15

Is alpha2 mainly a postsynaptic or presynaptic adrenoreceptor?

Answer 15

presynaptic

Question 16

What is the target of alpha2 adrenoreceptor binding?

Answer 16

nerve terminals

Question 17

Is NA binding at alpha2 adrenoreceptor excitatory or inhibitory?

Answer 17

inhibitory

Question 18

Considering the fact that NA binding at alpha2 has an inhibitory effect, what is another name for these receptors? Explain.

Answer 18

alpha2 = autoreceptor b/c it reduces its own release of NA

Question 19

Which type of adrenoreceptor is activated by adrenaline from the adrenal gland in addition to NA from sympathetic postganglionic nerves?

Answer 19

beta-adrenoreceptors

Question 20

What are the 3 beta-adrenoreceptors and what are their targets?

Answer 20

beta1: open Ca2+ channels (e.g. in heart)
beta2: relax vascular smooth muscle, dilate bronchioles
beta3: adipocytes

Question 21

TRUE or FALSE: presynaptic beta receptors decrease NA release.

Answer 21

FALSE: increase NA release

Question 22

In general, what are cholinergic effects and adrenergic effects?

Answer 22

cholinergic effects: relaxation of smooth muscle and secretion
adrenergic effects: contraction and inhibition of secretion

Question 23

Most visceral organs receive both parasympathetic and sympathetic innervation. Exceptions to this generalization include the ______, ______, _____, ____________, and most ______________ (only sympathetic).

Answer 23

spleen, kidney, liver, fat cells, blood vessels

Question 24

Describe the baroreceptor reflex. What is the trigger? What is the target effect?

Answer 24

trigger: low aortic bp –> effect: increase sympathetic outflow

trigger: high aortic bp –> effect: increase parasympathetic outflow

Question 25

What is the postural reflex?

Answer 25

standing up activates the baroreceptor reflex