[Biological role of cellular metabolites--structural analogs of platelet activating factor]

The review is concerned with cell metabolites - the platelet activating factor (PAF) and its choline-containing structural analogs. The biological activity of PAF and its analogs are considered. The influence of PAF and its analogs of membrane properties, cell receptors, transmembrane signalling (protein kinase C activation, Ca2+ release) as well as its participation in cell phospholipases A2, C and D activation are considered. The intracellular function of PAF and its analogs is discussed in terms of their influence on prostaglandin and leukotriene biosynthesis as well as with reference to the biological activity of 1-acyl-2-acetyl-sn-glycerols and lysophosphatidylcholine. The function of cell-released PAF and its analogs is considered in connection with their influence on plasma lipoproteins, inter-cell PAF synthesis and different mechanisms of PAF and PAF analog-induced cell activation including cell priming, cell desensitization and receptor-dependent effects. It is concluded that PAF is an intracellular and intercellular mediator, whereas 1-acyl-PAF is an intracellular lipid bioregulator.