Characterization of the reaction sequence involved in phospholipid labeling and deacylation and prostaglandin synthesis and actions.

The synthesis and release of prostaglandins (PG) primarily involve a series of enzymatic transformations of the fatty acid arachidonic acid. The source of this free fatty acid is thought to be the cleavage by phospholipase A2 of the acyl bond on the 2-position of phospholipids. The liberated arachidonic acid is primarily converted by cyclo-oxygenase (PG-synthetase) into the PG-endoperoxides (PGG2 and PGH2). These compounds represent a critical branch point in PG metabolism since they serve as substrates for the enzymatic synthesis of PGE2, PGD2, thromboxane A2, PGI2 (prostacyclin), as well as some likely products yet to be identified. The ultimate fate of arachidonate in a given tissue is determined by the repertoire of enzymes present. The prostaglandins have a very broad sprectum of identified biological activities and the newly discovered arachidonate metabolites (endoperoxides, thromboxane A2 and PGI2) are labile and extremely potent.