Platelet activating factor
Chapter: 2
PAF is produced by many different kinds of stimulated cells (e.g., basophils, neutrophils, monocytes, macrophages, endothelial cells) from phospholipids mobilized from cell membranes by phospholipase A2, i.e., PAF is not preformed in storage granules. Unlike the eicosanoids, which are also not stored in cells, PAF is not made from arachidonic acid. Chemically, it is an acetyl glycerol ether phosphocholine. It is 100-to-10,000 times more potent than histamine with respect to its vasoactive properties. As one of its smooth muscle effects, it is a strong bronchoconstrictor. It also stimulates other cells to increase their functional and metabolic activities, i.e., primes or activates them for more effective function.
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