Arachidonic Acid Flashcards
What are eicosaniods?
20-carbon non-hydrolyazble lipids that mediate biological processes in their immediate environment
What is the role of phospholipase A2?
catalyzes reaction of release of arachidonate from a glycerophospholipid
How does cortisone interfere with production of eicosanoids?
inhibits phospholipase A2
What is Thromboxane A2 (TXA2)?
a prostaglandin that enhances thrombus formation
What is prostacyclin (PGI2)?
inhibits thrombus formation
What is the function of PGI2, PGF3, and PGD2?
signal cAMP production which activates the cAMP-PKA pathway - inflammation via increasing vasodilation and blood flow to affected areas
What is the function of the Cox enzymes?
catalyze the reaction that turns arachidonate into PGH2, an unstable intermediate in the cyclooxyrgenase pathway from arachidonate to prostaglandins
How does aspirin exert its effect?
irreversibly inhibits Cox-1 and Cox-2 so that arachidonate cannot be converted into prostaglandins - reduces clotting response via reducing TXA2 in platelets
What prostaglandins does PGH2 give rise to?
TXA2 (thromboxane), PGI2 (prostacyclin), PGF2, PGE2
Why does Ibuprofen not have the same effect on platelets as aspirin does?
It is a reversible inhibition of Cox-1 enzyme whereas aspirin irreversibly inhibits Cox1 and platelets are not able to replenish cox-1 due to lack of a nucleus.
Why are Cox-2 inhibitors not used frequently given the stomach problems caused by Cox-1 inhibitors?
Cox-2 inhibitors disrupt the balance of TXA and PGI2 by inhibiting PGI2, which reduces thrombosis, and leaving TXA active to enhance thrombosis, which leads to increased MI and CVA
Why are people with asthma not supposed to use NSAIDs?
causes arachidonate pathway to shift towards the making of more leukotrienes, which induce bronchospasm inflammation
What does Cox-1 control?
prostaglandins for gastric protection, uterine contraction, and renal function & thromboxanes
