release of arachidonic acid
Last reviewed 01/2018
Arachidonic acid is stored in the membranes of body cells as an ester in phosphatidylcholine and phosphatidylinositol. To form secondary mediators, it must first be released by the action of two enzymes pathways:
- phospholipase A2
- or phospholipase C then diacylglycerol lipase
The phospholipase pathway also has a role in production of the precursor of platelet activating factor.
Stimulation for arachidonic acid production may be:
- physical stimuli e.g. cell damage
- mechanical stimuli
- a given agent in particular cells:
- C5a in neutrophils
- thrombin in platelets
- antigen-antibody complex on mast cells
Glucocorticoids produce their anti-inflammatory action mainly by producing a substance which inhibits phospholipase A2.