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Biochemistry Post Midterm > Eicosanoids > Flashcards

Flashcards in Eicosanoids Deck (41):
1

what are the 3 types of eicosanoids?

prostaglandins
thromboxanes
leukotrienes

2

which eicosanoids are associated with inflammation?

prostaglandins
thromboxanes

3

which eicosanoid is associated with allergic reaction/hypersensitivity?

leukotrienes

4

how do eicosanoids act and exert effects?

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

5

all cells except what synthesize eicosanoids?

erythrocytes!

6

where does arachidonic acid reside in the cell?

C-2 posotion of membrane phospholipids

7

how is arachidonic acid released from phospholipids?

phopholipase A2

8

what structures do eicosanoids affect in inflammatory responses?

joints, skin, eyes

9

what do eicosanoids play an important role in?

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

10

where are eicosanoids derived from?

arachidonic acid = 20C

11

where are minor eicosanoids dervied from?

alpha linolenic acid obtained from diet

12

what is another source of arachidonic acid?

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

13

what is the key enzyme in eicosanoid synthesis?

cyclooxygenase (COX1 and COX2)

14

what does cyclooxygenase (COX1 and COX 2) do?

converts arachidonic acid to PGG2 -- PGH2

15

what do eicosanoid products depend on?

cell type

16

what is the function of COX-1?

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

17

what is a corticosteroid? What do they inhibit?

potent steroidal anti-inflammatory drug

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

18

what omega family is arachidonic acid in?

omega 6

19

What does COX-2 do?

nonconstitutive
can be induced/upregulated to become more active

20

what can induce COX-2?

cytokines, GF, tumor promoters, endotoxins

21

what inhibits the expression of COX-2?

glucocorticoids

22

what does induction of COX 2 lead to ?

PG synthesis = pain, heat, redness, swelling fever

23

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

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

24

some selective COX2 inhibitors have been used to treat?

chronic inflammation associated with disease - celebrex

25

which are important to vascular health?

TXA2 and PGI2

26

what are platelets associated with?

COX 1

27

what is vascular endothelium associated with?

COX 1 and COX 2

28

what does aspirin do ? How?

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

29

how does low dose aspirin reduce thrombosis?

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

platelets cannot make new COX 1 enzyme - reduced TX synthesis

30

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

prostacyclin

31

a diet rich in EPA leads to incorporation of what ?

20:5, omega 3 into the human phospholipid membranes

32

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

EPA!

33

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

3 series from arachidonic acid to the 2 series

34

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

potent

PGI3 and PGI2 are about the same*

35

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

reduction of platelet aggregation/blood clotting

36

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

addition of GSH - glutathione (tripeptide)

37

what are the cysteinyl-leukotrienes?

LTC, LTD, LTE

38

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

cysteinyl-leurkotrienes

39

how does low dose aspirin favor bettwen CV health?

reducing platelet aggregation by increasing the ratio of PGI2 to TXA2

40

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

cortisol
prevent relase of arachidonic acid

41

what is the key enzyme in forming leukotrienes?

5-lipoxygenase