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Biochemistry Post Midterm > Eicosanoids > Flashcards

Eicosanoids Flashcards

1
Q

what are the 3 types of eicosanoids?

A

prostaglandins
thromboxanes
leukotrienes

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2
Q

which eicosanoids are associated with inflammation?

A

prostaglandins

thromboxanes

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3
Q

which eicosanoid is associated with allergic reaction/hypersensitivity?

A

leukotrienes

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4
Q

how do eicosanoids act and exert effects?

A

autocrine or paracrine = locally
through receptor-mediated G-protein linked signaling leading to an increase in either c-AMP or increase in intracellular Ca2+

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5
Q

all cells except what synthesize eicosanoids?

A

erythrocytes!

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6
Q

where does arachidonic acid reside in the cell?

A

C-2 posotion of membrane phospholipids

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7
Q

how is arachidonic acid released from phospholipids?

A

phopholipase A2

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8
Q

what structures do eicosanoids affect in inflammatory responses?

A

joints, skin, eyes

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9
Q

what do eicosanoids play an important role in?

A

inhibiting gastric acid secretion
regulation of BP - vasodil/vasocon
inhibit/activate platelet aggregation and thrombosis

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10
Q

where are eicosanoids derived from?

A

arachidonic acid = 20C

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11
Q

where are minor eicosanoids dervied from?

A

alpha linolenic acid obtained from diet

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12
Q

what is another source of arachidonic acid?

A

PIP2
its hydrolyzed by PLA2 which removes acyl chain t 2 position
it produces arachidonic acid and leave lyso-PIP2

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13
Q

what is the key enzyme in eicosanoid synthesis?

A

cyclooxygenase (COX1 and COX2)

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14
Q

what does cyclooxygenase (COX1 and COX 2) do?

A

converts arachidonic acid to PGG2 – PGH2

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15
Q

what do eicosanoid products depend on?

A

cell type

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16
Q

what is the function of COX-1?

A

its in most tissues
basal activity - always working constantly
produces PG and TX
constituative

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17
Q

what is a corticosteroid? What do they inhibit?

A

potent steroidal anti-inflammatory drug

inhibit the 1st step – inhibits PLA2 so no arachidonic acid is formed
selectively inhibit COX 2

18
Q

what omega family is arachidonic acid in?

A

omega 6

19
Q

What does COX-2 do?

A

nonconstitutive

can be induced/upregulated to become more active

20
Q

what can induce COX-2?

A

cytokines, GF, tumor promoters, endotoxins

21
Q

what inhibits the expression of COX-2?

A

glucocorticoids

22
Q

what does induction of COX 2 lead to ?

A

PG synthesis = pain, heat, redness, swelling fever

23
Q

how do non-steroidal anti-inflammatory drugs (NSAIDS) reduce inflammation?

A

inhibiting COX1 and COX 2 - reduce production of PG and TX

24
Q

some selective COX2 inhibitors have been used to treat?

A

chronic inflammation associated with disease - celebrex

25
Q

which are important to vascular health?

A

TXA2 and PGI2

26
Q

what are platelets associated with?

A

COX 1

27
Q

what is vascular endothelium associated with?

A

COX 1 and COX 2

28
Q

what does aspirin do ? How?

A

irreversibly inhibits COX 1 and COX 2 by acetylation of Serine residue in the active site!

29
Q

how does low dose aspirin reduce thrombosis?

A

reducing platelet aggregation due to decrease TX but it doesn’t reduce PGI2

platelets cannot make new COX 1 enzyme - reduced TX synthesis

30
Q

endothelial cells can synthesize new COX 1 and COX 2 enzyme so they can produce what?

A

prostacyclin

31
Q

a diet rich in EPA leads to incorporation of what ?

A

20:5, omega 3 into the human phospholipid membranes

32
Q

what can be used instead of arachidonic acid by PLA2 and used for eicosanoid synthesis?

A

EPA!

33
Q

what series do PG and TX formed from EPA belong to?

A

3 series from arachidonic acid to the 2 series

34
Q

TXA3 from EPA is less what compared to TXA2 in platelet aggregation?

A

potent

PGI3 and PGI2 are about the same*

35
Q

what does the net effect of PGI3 and TXA3 result in?

A

reduction of platelet aggregation/blood clotting

36
Q

how is LTA used in mast cells and eosinophils form LTC ?

A

addition of GSH - glutathione (tripeptide)

37
Q

what are the cysteinyl-leukotrienes?

A

LTC, LTD, LTE

38
Q

which are SRS-A and are much more potent than histamine?

A

cysteinyl-leurkotrienes

39
Q

how does low dose aspirin favor bettwen CV health?

A

reducing platelet aggregation by increasing the ratio of PGI2 to TXA2

40
Q

what do you want to give a patient with asthma attack and why?

A

cortisol

prevent relase of arachidonic acid

41
Q

what is the key enzyme in forming leukotrienes?

A

5-lipoxygenase

Biochemistry Post Midterm (24 decks)

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