Pharmacology
Eicosanoids
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Get accessFormed from arachidonic acid (via phospholipase action), a component of cell membrane phospholipids
- Main types
- Prostaglandins: subtypes
Prostacyclin: produced by endothelium and causes vasodilation and inhibition of thrombosis (aka prostaglandin I2)
- Sensitise nerve endings to pain (but don’t produce pain)
- Thromboxanes: vasoconstriction, platelet aggregation, bronchoconstriction
- Leukotrienes: subtypes
- Involved in allergic reactions and inflammation
- Bronchoconstriction, vasoconstriction and increased vascular permeability
- Initial rate-limiting step in their generation is mediated by phospholipase A2 or C
- Free arachidonic acid is metabolised by
- Cyclo-oxygenase: generating prostaglandins
Inflammatory prostaglandins are synthesised by COX-2 while gastroprotective prostaglandins are synthesised by COX-1
- Lipoxygenase: generates leukotrienes
- NSAIDs are cyclo-oxygenase inhibitors