Prostaglandins-COMP Flashcards
Prostaglandins act as
Local hormones.
Prostaglandins are synthesized in the body form the essentials fatty acids
Arachidonic acid
Dihydrolinoleic acid
Eicosapentaenoic acid
Arachidonic acid is a component of _________is released by
Cell membrane ; Action of phospholipase C and phospholipase A2
Phospholipase enzymes are inhibited by
Corticosteroids
Phospholipase A2 leads to
Arachidonic acid
Arachidonic Acid gives rise to 2 pathways
Cyclooxygenase and Lipooxygenase
Pathway of clyclooxygenase lead to
Endoperoxides leading to Thromboxane synthethase and prostacyclin synthethase, leading to thromboxane and prostacyclin
Pathway of Lipooxygenase lead to
5-Hydroxy-Arachidonic Acid –> Leukotrienes
Mechanism of Action of Prostaglandins
Stimulate synthesis of cyclic Adenosine monophosphate (cAMP) by activation of adenylate cyclase
cAMP activates protein A to express it effect, including decreased free intracellular concentration of calcium which leads to
Vascular relaxation
Act as filter fro many of the prostaglandins
Lungs
Half time of Thromboxane A2
30 seconds
Half time of Prostacyclin
3 minutes
Under strict regulation of prostacyclins
Normal platelet function and hemostasis
Regulated by prostaglandins
Renal blood flow
Prostaglandins maintain or increase
mucosal blood flow and help increase secretion mucus and bicarb in the stomach
What is the principal Cyclooxygenase product of arachidonic acid in platelet?
Thromboxane
Act as an intense stimulus for platelet aggregation and vasoconstriction
Thromboxane
Low doses of ASA
IRREVERSIBLY inhibits Thromboxane
NSAIDS
Reversible inhibited by NSAIDS
The most potent endogenous inhibitor of platelet aggregation and is a potent vasodilator
Prostacyclin
Doses needed to inhibit both thromboxane and prostacyclin production
Large doses of ASA
What is important in maintaining platelet activity and coagulation?
A normal Thromboxane to prostacyclin ratio
What can lead to decrease blood flow leading to possible ischemia or infarction of vital organs?
Increase thromboxane
Decrease prostacyclin
What can lead to Bleeding disorders?
Decrease Thromboxane
increase prostacyclin
What is the major site of prostaglandin synthesis?
The lungs
Can lead to bronchial asthma
Thromboxane and prostacyclin
Leukotrienes vs histamine
Leukotrienes have thousand times more potent bronchial smooth muscle vasoconstriction activity than histamine
ASA can lead to an increase in
production of leukotrienes
Intrarenal release of prostaglandins lead to
Modulate renal blood flow and GFR