Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry I > Chapter 30: Eicosanoids; Prostaglandins and Thomboxanes > Flashcards

Chapter 30: Eicosanoids; Prostaglandins and Thomboxanes Flashcards

1
Q

Pleiotropic action of eicosanoids

A
  • Vascular
  • Gastrointestinal
  • Reproductive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Prostaglandins and thromboxanes

A
  • Produced in all mammalian cells except RBCs
  • Oxygenated derivatives of polyunsaturated, long chain FAs
  • Produced rapidly from cell membrane in phospholipis in response to an event (not produced by an endocrine gland)
  • Short half-life (rapidly degraded)
  • Local homrones (paracrine mediatiors of inflammation and pain)
  • Act locally & rapidly degraded
  • Pleiotropic actions
  • G-protein linked receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Prostaglandin receptor mechanisms

A
  • Eicodanoids act rapidly in an autocrine and paracrine fashion
  • Bind to receptors on the cell surface
  • Receptor density and type on different cells determine specificity
  • Receptors are G protein-linked and contain sequences…..
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

cAMP production

A
  • Local hormone (prostaglandin) binds to receptor (most likely 7-pass serpentine receptor)
  • G-protein is activated, then activated adenylate cyclase
  • cAMP activates protein kinase A
  • Binding of cAMP to the regulatory subunit causes catalytic subunits to dissociate
  • Catalytic subunits can then go on to phosphorylate intracellular proteins
  • Active site of the enzyme is tucked away inside tetramer
  • When cAMP binds to regulatory subunits, catalytic subunits come apart and expose the active site
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Eicosanoids and IP3

A
  • Bind to receptors, activate G protein (in this case a GP or GQ)
  • GQ activates phospholipase C
  • Phospholipase C hydrolyzes PIP2 to IP3 and DAG
  • Prostaglandins exert hteir effects by bnidnig to cell surface receptors (mostly G protein linked)
  • DAG activates protein kinase C
  • IP3 binding causes PKC to move to the cell membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Arachidonic acid (C20:4) is derived from

A
  • Essential linoleic acid (omega-6 FA)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Essential fatty acid (C18:2) is abundant in

A
  • US diet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Arachidonic acid is a

A
  • 20 carbon (C20:4) FA

- Contains four double bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Arachidonate is present in

A
  • Membranes “stored” in phospholipids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Arachidonate is liberated by

A
  • Phospholipase A2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Arachidonic acid (C20:4) functions as

A
  • Proinflammatory

- Associated with pathology of endothelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Alpha-linoleic acid (omega-3) functions as

A
  • Cardio-protective fatty acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Arachidonic acid (C20:4) activates

A
  • Protein kinase C
  • Phospholipase D
  • Functions as a signaling molecule itself
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Liberation of arachidonate

A
  • Released form membrane phospholipids by phospholipase A2 (rate limiting)
  • Can also be released by a combination of phopsholipase C and diacylglycerol lipase or phopsholipase C, diacylglycerol kinase and phospholipase A2
  • Anti inflammatory drufs inhibit these lipase pathways thereby explaining their potent anti-inflammatory proterties
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Oxygenation of arachidonic acid

A
  • After liberation from a phopsholipid, arachidonic acid may be oxygenated
  • The cyclooygenase pathway leading to prostaglanding and thomboxanes
  • Lipoxygenase pathway leading to leukotrienes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In circulatory system

A
  • Endothelial cells are producing prostocylin

- Produced in enothedelial cells, prostocyclin keeps blood veseels open and favors blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Platelets producing thromboxane A2 mediate

A
  • Vasoconstricton
18
Q

Arachidonic acid is the majore percursor of

A
  • Eicosanoids

- PGH2 is unstable and rapidly broken down

19
Q

Cyclooxygenase pathway

A
  • 3 unique but related cyclooxygenase isoenzymes convert arachidonic acid to unstable postalgandin endoperoxide, PGH2
20
Q

Cycloogygenase I (COX I)

A
  • Constitutive
  • House keeping
  • Permanently turned on (good things we want COX to do)
  • Maintain blood flow, protect stomach, etc.
21
Q

Cyclooxygenase II (COX II)

A
  • Inducible (induced in macrophages and other cells)
  • Inflammatory/trauma response
  • Overproduced in response to inflammation/trauma without affecting COX I
22
Q

COX III

A
  • Found in heart and kidney

- Inhibited by acetaminophen

23
Q

Regulation of blood flow

A
  • Blood pressure and coagulation
  • PGI2 (endothelium - v/d) vs TXA2 (platelets - v/c)
  • Aortic thromboxane levels increase during MI
24
Q

PGE2 inhibition of acid secretion and stimulates mucus secretion

A
  • Cytoprotection

- Eicosanoid levels elevated in rectal mucosa and stool in inflammatory bowel disease

25
Q

Promote luteolysis and regulation of female reproductive cycle

A
  • Induce labor
26
Q

Eicosanoids

A
  • Stimulation of inflammation

- Modulation of synaptic transmission

27
Q

Pleiotropic action of eicosanoids involves

A
  • Regulation of blood flow
  • PGE2 inhibition of acid secretion & stimulates mucus secretion
  • Promote luteolysis and regulation of female reproductive cycle
  • Stimulation of inflammation
  • Modulation of synaptic transmission
28
Q

Regulation of platelet and endothelial cell interactions occurs by

A
  • TXA2

- PGI

29
Q

If endothelial cells become damaged

A
  • Significant amounts of platelet aggregation try to plug the leak
  • Overproduce thromboxane A2
  • Levels of prostacyclin are diminished
30
Q

Once endothelial cells are repaired after damage

A
  • Equilibrium of thromboxane A2 and prostacyclin activity is restored
31
Q

Inhibition of eicosanoid production occurs via

A
  • Anti-inflammatory drugs
32
Q

NSAIDS

A
  • Exert their effects by inhibiting COX activity
33
Q

Aspiring

A
  • Irreversibly acetylates specific serine moieties on both COX enzymes
  • Inhibits COX I and modifies activity of COX II
34
Q

Ibuprofen (Advil)

A
  • Inhibits COX I and II non-covalently
35
Q

Corticosteroids (lke prednisone)

A
  • Block eicosanoid synthesis, perhaps by stimulating the synthesis of several inhibitory proteins called annexins (target phospholipase A2)
36
Q

Corticosteriods

A
  • PLase A2
37
Q

John Vane was responsible for

A
  • Aspirin = COX inhibition
  • Colon cancer?
  • Myocardial infraction
  • GIT toxicity is a problem
  • Worked to identify the target to these drugs
38
Q

Ibuprofen inhibits

A
  • COX I and COX II (non-covalent)
39
Q

Specific COX II inhibitors sort

A
  • After

- Remember the Vioxx story

40
Q

Anti-inflammatory drugs target

A
  • Eicosanoid synthesis
41
Q

Both prostaglandins and leukotrienes are derived from

A
  • Membrane phospholipid; arachidonic acid
42
Q

Aspirin and other nonsteroidal antiinflammatory drugs (NSAIDS) and corticosteroids inhibit

A
  • Eicosanoid production

Biochemistry I (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions