Prostaglandins/Eicosanoids Flashcards
Define eicosanoids
Produced by every tissue, specific types vary widely. Metabolic products of unsaturated membrane fatty acids.
Eicosanoids are synthesized and released in response to what?
Inflammatory, mechanical, neurological, or hormonal stimuli.
Eicosanoid half-life: short or long?
Very short.
Eicosanoid: act where in relation to where they are released?
Act very close to where they are released due to short half-life. Local autocrine or paracrine hormones.
What will induce expression of COX-2?
Inflammatory signals: IL1, TNF, LPS.
Eicosanoids do what with pain sensitivity?
Do not produce pain directly, but increase tissue sensitivity to other stimuli.
Eicosanoids do what with edema?
Enhance edema caused by bradykinin, histamine, C5a.
Eicosanoids and platelet function: what is stimulated by COX-1?
2 pathways:
- Thromboxane A2. stimulates platelet aggregation and vasoconstriction.
- PGE1. GI protection.
What is the effect of PGI2?
Produced by vascular endothelial cells via COX2. Inhibits platelet aggregation and causes vasodilation.
What is the effect of aspirin on COX1 and COX2?
Irreversibly inhibits COX1 and COX2. Platelets cannot synthesize new COX1 –> thromboxane production is impaired.
If aspirin is on board, how will you get new COX and therefore thromboxane for platelet aggregation and vasoconstriction?
Endothelial cells can synthesize new COX1 and COX2.
I and E prostaglandins do what in fetus?
Maintain ductus arteriosus patency.
E and I prostaglandins do what to arterial blood pressure?
Reduce arterial blood pressure by direct vasodilation, modulating norepinephrine release, modulating renal hormones.
What are Coxibs?
Selective COX2 inhibitors.
What is the role of Coxibs?
increase thrombosis by selectively inhibiting prostacyclin but NOT thromboxane (stimulates platelet agg and vasoconstriction).
