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Pharmacology FINAL > Lecture 7 Part 3 > Flashcards

Lecture 7 Part 3 Flashcards

1
Q

explain how norepinephrine is synthesized

A

tyrosine and sodium are transported into the nerve terminal by an A transporter

tyrosine hydroxylase catalyzes the conversion of tyrosine to Dopa, which then becomes DOPAMINE through Dopa decarboxylase

Dopamine enters a vesicle through VMAT in exchange for a hydrogen ion. there, it gets converted to NOREPINEPHRIN by Dopamine B-hydroxylase

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2
Q

what can inhibit tyrosine hydroxylase?

A

metyrosine

tyrosine won’t be converted to Dopa and NE can’t be synthesized

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3
Q

what can inhibit the transport of dopamine into a vesicle through VMAT transporter?

A

Reserpine

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4
Q

explain the release of norepinephrine

A

released also through the influx of calcium and VAMPS/SNAPS

binds to ADRENOCEPTORS

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5
Q

after NE has been synthesized and released, explain its potential fates

A

-usually recycled back into the nerve terminal through NET (norepinephrine transporter)

-can be released by diffusion and broken down (after binding adrenoceptors)

-can bind back to NE autoreceptor

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6
Q

what inhibits the release of NE in vesicles by blocking VAMPS and SNAPS

A

bretylium and guanethidine

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7
Q

what blocks the reuptake of norepinephrine through NET?
what is the result of this?

A

cocaine
tricyclic antidepressants

this causes NE to stay in the synaptic cleft for longer and binds to the postsynaptic neuron for a longer period of time

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8
Q

in which cases is norepinephrine the final product?
in which cases is epinephrine the final product?
in which cases is DOPAMINE the final product?

A

NE in MOST sympathetic postganglionic neurons

in the adrenal medulla and certain areas of the brain - epinephrine

in dopaminergic neurons - ends with dopamine synthesis

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9
Q

how is NE converted to epinephrine and where does this occur?

A

through Phenylethanolamine-N-methyltransferase

occurs mainly in adrenal medulla and some areas of the brain

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10
Q

true or false

phenylethanolamine-N-methyltransferase is a phase 2 enzyme

A

true

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11
Q

normally, what is the ration of norepinephrine to epinephrine

A

80% NE
20%E

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12
Q

besides going through dopamine, explain another pathway of NE synthesis, starting from tyrosine

A

tyrosine is converted to tyramine by L-amino acid decarboxylase

Tyramine is converted to Octopamine by Dopamine B-hydroxylase

Octopamine is converted to NE through Hydroxylase from the liver

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13
Q

can NE ever be released through a calcium INDEPENDENT process?

A

yes

indirectly acting and mixed sympathomimetics such as tyramine, amphetamines, and ephedrine

excellent substrate for monoamine transporter and are taken inside the nerve terminal and remove NE from vesicles and release it

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14
Q

____________ inhibits monoamine oxidase and enhances NE and dopamine neurotransmission

A

Amphetamine

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15
Q

what does amphetamine do in relation to NE?

A

inhibits monoamine oxidase and enhances NE and dopamine neurotransmission

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16
Q

how many ways can noradrenergic transmission be terminated ? name them

A

2:

reuptake into the nerve terminal by NET or into other cells

simple diffusion away from the receptor site (eventually metabolized in the plasma or liver)

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17
Q

what is the RATE LIMITING STEP in catecholamine synthesis?

A

the conversion of tyrosine to dopa by tyrosine hydroxylase

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18
Q

the rate limiting step of catecholamine synthesis can be inhibited by…..

A

metyrosine

19
Q

what is VMAT?
what can inhibit it?

A

VMAT = vesicular monoamine transporter
-importer for catecholamines into the vesicle

can be inhibited by RESERPINE ALKALOIDS

20
Q

True or false

NET is partially responsivle for the termination of synaptic activity of norepinephrine

A

true

21
Q

the _______ and the endocrine system are integrated

A

ANS

22
Q

what is the function of aldosterone

A

to maintain fluid in the body

23
Q

what are autoreceptors?

A

presynaptic receptors that respond to the primary transmitter substance released by the nerve ending

part of negative feedback loop

24
Q

what are heteroreceptors?

A

regulatory receptors on nerve terminals that respond to many substances other than the primary neurotransmitter

25
Q

how do local anesthetics, tetrodotoxin, and saxitoxin affect neurotransmitter synthesis?
name its site

A

they affect the propagation of an action potential by blocking voltage gated sodium channels and blocking conduction
located in nerve axons

26
Q

explain what type of drugs inhibit transmitter synthesis and how

A

metyrosine - inhibits tyrosine hydroxylase and blocks catecholamine synthesis

hemicholiniums – blocks the uptake of choline, resulting in slow synthesis

27
Q

what is the site of hemicholiniums?

A

cholinergic nerve terminals
membrane

28
Q

what is the site of metyrosine?

A

adrenergic nerve terminals
adrenal medulla
cytoplasm

29
Q

what drugs affect transmitter storage and how?

A

vesamicol - prevents the storage and depletes

reserpine - prevents the storage and depletes

30
Q

explain the site of vesamicol and reserpine

A

vesamicol – cholinergic terminals, VAT on vesicles

reserpine - adrenergic terminals, VMAT on vesicles

31
Q

what drugs affect transmitter RELEASE? what is their site?

A

MANY DRUGS - nerve terminal membrane receptors. modulate the release of the transmitter

w-conotoxin GVIA4 in particular works at nerve terminal calcium channels and thus reduces transmitter release

botulinum toxin prevents the release of acetylcholine from cholinergic vesicles

32
Q

what is a-latrotoxin?
what is its site and what does it do?

A

located at cholinergic and adrenergic vesicles

affects transmitter release by causing explosive transmitter release

33
Q

name 2 drugs that PROMOTE neurotransmitter release

where are they located?

A

located at adrenergic nerve terminals

tyramine and amphetamine

34
Q

name drugs that inhibit the reuptake of NE through NET at adrenergic nerve terminals

what is the effect?

A

cocaine
tricyclic antidepressants
SNRI antidepressants

results in INCREASED NE EFFECT on the postsynaptic receptors

35
Q

what is the effect of NE on alpha receptors?

A

causes contraction

36
Q

what is the effect of phentolamine on alpha receptors?

A

PREVENTS the activation of alpha receptors

37
Q

name 2 drugs that act on alpha receptors and their function

A

norepinephrine binds alpha receptors and causes contraction

phentolamine binds alpha receptors and prevents their activation

38
Q

name 2 drugs that bind adrenergic Beta receptors and their effect

A

isoproteronol - activates adenylyl cyclase

propanolol - binds beta receptors and PREVENTS their activation

39
Q

explain the action of nicotine

A

binds nicotinic receptors and opens ion channels in the postsynaptic membrane

40
Q

what is the location of nicotinic receptors

A

nicotinic cholinergic junctions in autonomic ganglia and neuromuscular end plates

41
Q

explain the action of Tubocurarine

A

prevents the activation of nicotinic receptors at neuromuscular end plates

42
Q

name 2 drugs that bind muscarinic receptors and explain what they do

A

bethanechol - activates muscarinic receptors

atropine - binds muscarinic receptors and PREVENTS their activation

43
Q

name the sites of bethanechol and atropine

A

muscarinic parasympathetic effector cells, such as smooth muscle and glands

44
Q
A

Pharmacology FINAL (11 decks)

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